Tag: Scientists

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Health

CDC masks pointers may improve threat of spreading Covid at work and in public, scientists say

CDC mask guidelines could increase risk of spreading Covid at work and in public, scientists say

People without a mask are walking in Times Square in New York City on May 19, 2021.

John Smith | VIEW press | Corbis News | Getty Images

The CDC’s new mask guidelines could actually increase the risk of Covid-19 spreading in public spaces and workplaces, scientists from a leading group of infectious diseases said Thursday.

The Centers for Disease Control and Prevention abruptly reversed their mask guidelines for vaccinated Americans last week to say that vaccinated people will no longer need to wear a mask indoors or outdoors in most settings. Officials said they changed their guidelines in part because research shows the vaccines offer very high levels of protection against the disease of Covid-19 and spread it to others.

“There is no debate about this fact,” said Dr. Jeffrey Duchin, who sits on the CDC’s Advisory Committee on Immunization Practices, at a news conference hosted Thursday by the Infectious Diseases Society of America. However, the agency’s announcement created widespread confusion and frustration because “it was unexpected and lacked the necessary context for implementation by the state and local health community,” he said.

Duchin is the society’s liaison with the CDC’s Vaccination Committee. The company represents leading specialists in infectious diseases in the USA

“There was no information on how the guidelines could be used in practice, particularly in relation to the inability to check vaccination status,” said Duchin. The CDC also did not provide guidance on whether people should continue to wear masks in areas with high transmission rates or low vaccination rates, he said. “What the CDC did, however, was not optimal and gave the wrong impression that the mask mandates were being lifted.”

Doctors across the country and federal health officials continue to stress that only vaccinated people are safe to remove their masks. The new mask management was misinterpreted as the end of the pandemic and mask mandates, which puts the local health authorities in a very difficult position. States in the United States took the news as a cue to facilitate mask mandates. Texas Governor Greg Abbott used the new guidance to justify signing an executive order that threatens the fine for local officials and communities for not dropping mask requirements.

Duchin said that both vaccinated and unvaccinated people are likely safe outdoors without masks, but they are not indoors.

“Now the risk of Covid-19 spreading in crowded indoor spaces with unvaccinated people and especially with poor ventilation is increased,” said Duchin. While the CDC’s scientific basis for the change is “solid,” Duchin said ending the mandate for inner masks “could lead to increased risk in public spaces and workplaces with avoidable spread of Covid-19, mostly among the unvaccinated spreads. “

Vaccination rates vary across the country, and the majority of those vaccinated are older adults. Large subgroups such as younger adults remain unvaccinated.

Dr. Jeanne Marrazzo, who also spoke at the briefing, said research has shown that up to 3% of Americans have been told by their doctors that they have some level of immunodeficiency, which puts them at an increased risk of being exposed to Covid be.

“Millions of people fit that bill, and we literally have very little data on whether the vaccine works in them,” Marrazzo said. “There is a real reason to be careful and interpret the guidelines carefully.”

The scientists also said people need to acknowledge that there is uncertainty about the future course of the pandemic, the effects of emerging variants, the duration of immunity, and the potential for a Covid-19 resurgence.

“The Covid-19 outbreak is by no means over, there is still significant uncertainty and there is still significant disease activity,” said Duchin.

If someone is fully vaccinated and doesn’t have other conditions that threaten their community, and if the rate of Covid where they live is relatively low and the vaccination rate is high, Marrazzo said it would be “100% okay, pretty much anywhere without one. ” Mask.”

Marrazzo added that despite being fully vaccinated, she will continue to wear a mask around the house as vaccination rates in her community are not even 50%.

“If I knew we were seeing really notable decreases in hospital stays and symptomatic illnesses that may be related to Covid and that have a very high vaccination rate, I would probably go without a mask, but I won’t see this anytime soon,” she said.

While nearly half of all people in the United States, 160.2 million, received at least one shot, Marrazzo said only 4.6% of the world’s population did the same.

“People need to be aware of what’s going on and watch out for vaccination rates, look for the involvement of these new varieties and think about being ready to get things going again,” warned Marrazzo.

Correction: This story has been updated to reflect that the press conference was hosted by the Infectious Diseases Society of America.

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Health

Virus Variants Threaten to Draw Out the Pandemic, Scientists Say

Virus Variants Threaten to Draw Out the Pandemic, Scientists Say

Seit Wochen ist die Stimmung in weiten Teilen der USA lebhaft. Fälle, Krankenhausaufenthalte und Todesfälle durch das Coronavirus sind stark von ihren Höchstständen gefallen, und täglich werden Millionen von Menschen neu geimpft. Restaurants, Geschäfte und Schulen haben wieder geöffnet. Einige Staaten, wie Texas und Florida, haben die Vorsichtsmaßnahmen ganz aufgegeben.

Auf messbare Weise gewinnen Amerikaner den Krieg gegen das Coronavirus. Leistungsstarke Impfstoffe und ein beschleunigter Rollout garantieren beinahe eine Rückkehr zur Normalität – zu Gartengrills, Sommercamps und Übernachtungen.

Es wird jedoch zunehmend klarer, dass die nächsten Monate schmerzhaft sein werden. Sogenannte Varianten breiten sich aus und tragen Mutationen, die das Coronavirus sowohl ansteckender als auch in einigen Fällen tödlicher machen.

Selbst als Ende letzten Jahres Impfstoffe zugelassen wurden, die einen Weg zum Ende der Pandemie aufzeigten, waren Varianten Großbritanniens, Südafrikas und Brasiliens betroffen. Es sind immer wieder neue Varianten aufgetaucht – in Kalifornien in einer Woche, in New York und Oregon in der nächsten. Diese neuen Versionen des Coronavirus drohen, ein Ende der Pandemie zu verschieben, wenn sie Wurzeln schlagen.

Im Moment scheinen die meisten Impfstoffe gegen die Varianten wirksam zu sein. Die Beamten des öffentlichen Gesundheitswesens sind jedoch zutiefst besorgt darüber, dass künftige Iterationen des Virus möglicherweise resistenter gegen die Immunantwort sind und die Amerikaner sich für regelmäßige Auffrischungsrunden oder sogar neue Impfstoffe anstellen müssen.

“Wir haben keine Evolution auf unserer Seite”, sagte Devi Sridhar, Professor für öffentliche Gesundheit an der Universität von Edinburgh in Schottland. “Dieser Erreger scheint sich immer so zu verändern, dass es uns schwerer fällt, ihn zu unterdrücken.”

Gesundheitsbeamte erkennen die dringende Notwendigkeit an, diese neuen Viren zu verfolgen, wenn sie durch die Vereinigten Staaten kriechen. Bereits jetzt steigt B.1.1.7, die hoch ansteckende Variante, die Großbritannien ummauerte und in Kontinentaleuropa Chaos anrichtet, in den Vereinigten Staaten exponentiell an.

Begrenzte Gentests haben mehr als 12.500 Fälle ergeben, viele davon in Florida und Michigan. Ab dem 13. März machte die Variante landesweit etwa 27 Prozent der Neuerkrankungen aus, gegenüber nur 1 Prozent Anfang Februar.

Die Regierung von Biden hat eine „Anzahlung“ in Höhe von 200 Millionen US-Dollar zugesagt, um die Überwachung zu beschleunigen. Diese Infusion soll es ermöglichen, wöchentlich 25.000 Patientenproben auf Virusvarianten zu analysieren. Es ist ein ehrgeiziges Ziel: Das Land sequenzierte im Dezember nur wenige hundert Proben pro Woche und skalierte ab dem 27. März auf etwa 9.000 pro Woche.

Bis vor kurzem wurde der Anstieg von B.1.1.7 durch sinkende Infektionsraten insgesamt getarnt, was die Amerikaner in ein falsches Sicherheitsgefühl wiegte und zu vorzeitig gelockerten Beschränkungen führte, sagen Forscher.

“Der beste Weg, über B.1.1.7 und andere Varianten nachzudenken, besteht darin, sie als separate Epidemien zu behandeln”, sagte Sebastian Funk, Professor für Dynamik von Infektionskrankheiten an der London School of Hygiene and Tropical Medicine. “Wir verdunkeln die Sicht wirklich, indem wir sie alle addieren, um eine Gesamtzahl von Fällen zu erhalten.”

Andere in Südafrika und Brasilien identifizierte Varianten sowie einige erstmals in den USA beobachtete Virusversionen verbreiteten sich langsamer. Aber auch sie sind besorgniserregend, weil sie eine Mutation enthalten, die die Wirksamkeit der Impfstoffe verringert. Erst diese Woche erzwang ein Ausbruch von P.1, der Variante, die Brasilien zerschmetterte, die Schließung des Skigebiets Whistler Blackcomb in British Columbia.

Die Welt befindet sich in einem Sprint zwischen Impfstoffen und Varianten, und die Schüsse werden schließlich gewinnen, sagen Wissenschaftler. Da sich das Coronavirus bei jeder Infektion weiterentwickeln kann, müssen Impfungen in den USA und anderswo so schnell wie möglich durchgeführt werden.

Die Infektionen nehmen wieder zu, was durch B.1.1.7 und andere Varianten in ungewissem Maße bedingt ist. Anfang dieser Woche bat Dr. Rochelle Walensky, Direktorin der Zentren für die Kontrolle und Prävention von Krankheiten, die Amerikaner, weiterhin Maskierung und soziale Distanzierung zu üben, und sagte, sie habe das Gefühl eines „bevorstehenden Untergangs“.

“Wir dürfen uns so sehr freuen – so viel Versprechen und Potenzial, wo wir sind, und so viel Grund zur Hoffnung”, sagte sie. “Aber im Moment habe ich Angst.”

Das Coronavirus sollte sich nur langsam verändern. Wie alle Viren würde es Mutationen aufnehmen und sich zu Tausenden von Varianten entwickeln, sagten Wissenschaftler zu Beginn der Pandemie. Aber es würde sich jahrelang nicht wesentlich ändern – ein dummes Virus, wie manche es nannten.

Der Erreger widersetzte sich diesen Vorhersagen. “Wir haben erwartet, dass sich das Virus ändert”, sagte Dr. Michael Diamond, ein viraler Immunologe an der Washington University in St. Louis. “Wir haben nicht genau erwartet, wie schnell es passieren wird.”

Eine Variante ist nur dann von Belang, wenn sie ansteckender ist, schwerere Krankheiten verursacht oder die Immunantwort abschwächt. Die in Großbritannien, Südafrika, Brasilien und Kalifornien identifizierten Varianten erfüllen alle die Kriterien.

B.1.1.7, das als erstes allgemein bekannt wurde, ist nach jüngsten Schätzungen etwa 60 Prozent ansteckender und 67 Prozent tödlicher als die ursprüngliche Form des Virus.

Aktualisiert

3. April 2021, 15:04 Uhr ET

Die Variante unterscheidet sich nicht von der ursprünglichen, wie sie sich verbreitet, aber infizierte Menschen scheinen mehr und länger vom Virus zu tragen, sagte Katrina Lythgoe, eine Evolutionsbiologin an der Universität von Oxford. “Sie sind für mehr Tage ansteckender”, sagte sie.

B.1.1.7 ist so ansteckend, dass es Großbritannien erst nach fast drei Monaten strenger Anweisungen für den Aufenthalt zu Hause und einem aggressiven Impfprogramm gelungen ist, Infektionen zu bekämpfen. Trotzdem fielen die Fälle viel langsamer als bei einer ähnlichen Sperrung im März und April.

In Kontinentaleuropa bildete sich monatelang eine Welle von B.1.1.7-Fällen, die unter einer stetigen Abwanderung von Infektionen meist unbemerkt blieb. Die Variantenwelle erklimmt jetzt.

Polens Rate an täglichen Neuerkrankungen hat sich seit Mitte Februar verfünffacht, was die Schließung der meisten öffentlichen Veranstaltungsorte erzwingt. Deutschlands hat sich verdoppelt und ein Verbot von nächtlichen Versammlungen in Berlin ausgelöst.

In Frankreich, wo B.1.1.7 drei Viertel der Neuinfektionen verursacht, mussten einige Krankenhäuser Coronavirus-Patienten nach Belgien bringen, um Betten freizugeben. In Europa sterben jeden Tag ungefähr so ​​viele Menschen an Covid-19 wie vor einem Jahr.

Zu lange ignorierten Regierungsbeamte die Bedrohung. “Fallplateaus können die Entstehung neuer Varianten verbergen”, sagte Carl Pearson, ein wissenschaftlicher Mitarbeiter an der London School of Hygiene and Tropical Medicine. “Und je höher diese Hochebenen sind, desto schlimmer ist das Problem.”

In den Vereinigten Staaten begannen die Coronavirus-Infektionen im Januar rapide abzunehmen, was viele Staatsoberhäupter bald dazu veranlasste, Geschäfte wieder zu eröffnen und Beschränkungen zu lockern. Wissenschaftler warnten jedoch wiederholt davor, dass der Tropfen nicht von Dauer sein würde. Nachdem die Rate Mitte März bei etwa 55.000 Fällen und 1.500 Todesfällen pro Tag ihren Tiefpunkt erreicht hatte, verzeichneten einige Bundesstaaten – insbesondere Michigan – einen Anstieg.

Seitdem sind die nationalen Zahlen stetig gestiegen. Ab Samstag lag die tägliche Zahl bei fast 69.000, und der wöchentliche Durchschnitt lag um 19 Prozent über dem Wert von zwei Wochen zuvor.

Selbst wenn die Fälle zurückgingen, stellten die Forscher die Vorstellung in Frage, dass Impfungen der Grund seien. Millionen von Amerikanern werden jeden Tag geimpft, aber selbst jetzt haben nur 31 Prozent eine Einzeldosis eines Impfstoffs erhalten, und nur 17 Prozent der Bevölkerung haben vollen Schutz, so dass eine große Mehrheit anfällig ist.

“Tatsache ist, dass wir immer noch in einer Position sind, in der wir nicht genug geimpfte Menschen haben”, sagte Kristian Andersen, Virologe bei Scripps Research in San Diego. „Und wenn wir wie Texas sagen, dass wir mit Covid-19 fertig sind, wird B.1.1.7 hereinkommen und uns daran erinnern, dass wir nicht richtig liegen. Ich habe keinen Zweifel.”

Die Variante ist besonders in Florida verbreitet, wo der Staat die Beschränkungen aufhob und zunächst keinen Anstieg verzeichnete. Beamte in anderen Staaten führten dies als Begründung für die Wiedereröffnung an. Aber jetzt steigt Floridas Infektionsrate nach oben.

Die Variante wurde möglicherweise nur durch das verdeckt, was Wissenschaftler gerne als Saisonalität bezeichnen. Infektionen der Atemwege sind in Florida im Frühjahr normalerweise selten, bemerkte Sarah Cobey, Evolutionsbiologin an der Universität von Chicago. Coronavirus-Infektionen erreichten im Sommer letzten Jahres in Florida ihren Höhepunkt, als die Hitze die Menschen in Innenräumen trieb und dies möglicherweise erneut tun wird.

“Ich glaube immer noch nicht, dass wir nicht im Wald sind”, sagte Dr. Cobey und bezog sich auf das ganze Land. “Wenn wir diesen Frühling keine weitere Welle haben, werde ich mir wirklich große Sorgen um den Herbst machen.”

Während die meisten Impfstoffe gegen B.1.1.7 wirksam sind, sind Forscher zunehmend besorgt über andere Varianten, die eine Mutation namens E484K enthalten. (Wissenschaftler bezeichnen es oft angemessen als “Eek”.)

Diese Mutation hat sich in vielen Varianten weltweit unabhängig entwickelt, was darauf hindeutet, dass sie dem Virus einen starken Überlebensvorteil bietet.

In Laborstudien scheinen die Impfstoffe Pfizer-BioNTech und Moderna gegen B.1.351, die in Südafrika identifizierte Variante, etwas weniger wirksam zu sein. Diese Variante enthält die Eek-Mutation, die es dem Virus zu ermöglichen scheint, die Immunantwort des Körpers teilweise zu umgehen. Die von Johnson & Johnson, AstraZeneca und Novavax hergestellten Impfstoffe waren gegen B.1.351 noch weniger wirksam.

“Ich denke, für die nächsten ein oder zwei Jahre wird E484K die am meisten besorgniserregende Mutation sein”, sagte Jesse Bloom, Evolutionsbiologe am Fred Hutchinson Cancer Research Center in Seattle.

Die Mutation verändert das sogenannte Spike-Protein, das auf der Oberfläche des Coronavirus sitzt, geringfügig, was es für Antikörper nur ein wenig schwieriger macht, sich an den Eindringling zu binden und ihn zu zerstören.

Die gute Nachricht ist, dass das Virus nur ein paar Überlebenstricks in der Tasche zu haben scheint, und das erleichtert es Wissenschaftlern, diese Abwehrkräfte zu finden und zu blockieren. “Ich fühle mich ziemlich gut bei der Tatsache, dass es nicht so viele Möglichkeiten gibt”, sagte Michel Nussenzweig, Immunologe an der Rockefeller University in New York.

Die Eek-Mutation scheint die primäre Abwehr des Virus gegen das Immunsystem zu sein. Forscher in Südafrika berichteten kürzlich, dass ein neuer Impfstoff gegen B.1.351 auch alle anderen Varianten abwehren sollte.

Pfizer, BioNTech und Moderna testen bereits neu entwickelte Booster-Shots gegen B.1.351, die gegen alle Varianten wirken sollen, von denen bekannt ist, dass sie die Immunantwort abschwächen.

Anstelle eines neuen Impfstoffs gegen Varianten könnte es für Amerikaner jedoch genauso effektiv sein, innerhalb von sechs Monaten bis zu einem Jahr eine dritte Dosis der Pfizer-BioNtech- oder Moderna-Impfstoffe zu erhalten, sagte Dr. Anthony S. Fauci, Leiter des National Institut für Allergien und Infektionskrankheiten.

Dies würde die Antikörperniveaus bei jedem Empfänger hoch halten und jede Variante überwältigen – eine praktischere Strategie als die Herstellung eines speziellen Impfstoffs für jede neue Variante, sagte er.

“Meine einzige Sorge bei der Jagd nach allen Varianten ist, dass Sie fast Whac-A-Mole spielen würden, wissen Sie, weil sie immer wieder auftauchen”, sagte Dr. Fauci.

In der einen oder anderen Form wird das neue Coronavirus bleiben, glauben viele Wissenschaftler. Im Land können mehrere Varianten gleichzeitig im Umlauf sein, wie dies bei Erkältungs-Coronaviren und Influenza der Fall ist. Um sie in Schach zu halten, ist möglicherweise ein jährlicher Schuss erforderlich, wie z. B. der Grippeimpfstoff.

Der beste Weg, um die Entstehung gefährlicher Varianten zu verhindern, besteht darin, die Fälle jetzt gering zu halten und die große Mehrheit der Welt – nicht nur die Vereinigten Staaten – so schnell wie möglich zu immunisieren. Wenn bedeutende Taschen der Welt ungeschützt bleiben, wird sich das Virus auf gefährliche neue Weise weiterentwickeln.

“Dies könnte etwas sein, mit dem wir uns noch lange befassen müssen”, sagte Rosalind Eggo, Epidemiologin an der London School of Hygiene and Tropical Medicine.

Dennoch fügte sie hinzu: “Auch wenn es sich wieder ändert, was sehr wahrscheinlich ist, sind wir in einer besseren, viel stärkeren Position als vor einem Jahr, um damit umzugehen.”

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World News

Can Vaccinated Individuals Unfold the Virus? We Don’t Know, Scientists Say.

Can Vaccinated People Spread the Virus? We Don’t Know, Scientists Say.

The Centers for Disease Control and Prevention responded Thursday to controversial comments from their director, Dr. Rochelle P. Walensky, back and suggested that people vaccinated against the coronavirus never get infected or pass the virus on to others.

The claim challenged the precautions the agency had urged vaccinated individuals to take just last month, such as wearing masks and collecting only in limited circumstances with unvaccinated individuals.

“DR. Walensky spoke broadly during this interview,” an agency spokesman told The Times. “It is possible that some people who are fully vaccinated will get Covid-19. The evidence is not clear as to whether they have the virus others can transfer. We continue to evaluate the evidence. “

The agency responded in part to criticism from scientists who found that current research is nowhere near enough to suggest that vaccinated people cannot spread the virus.

The data suggests that “vaccinated people are much harder to get infected, but don’t think for a second they can’t get infected,” said Paul Duprex, director of the Center for Vaccine Research at the University of Pittsburgh.

In a television interview with MSNBC’s Rachel Maddow, Dr. Walensky responded to data released by the CDC showing that one dose of the Moderna or Pfizer BioNTech vaccine was 80 percent effective and two doses were 90 percent effective.

This certainly indicated that transmission from vaccinated people might be unlikely, but Dr. Walensky’s comments indicated that the protection was complete. “Our data from the CDC today suggests that vaccinated people do not carry the virus and do not get sick,” she said. “And not only in clinical studies, but also in real data.”

Dr. Walensky also stressed the importance of continuing to wear masks and taking precautions, including for people who have been vaccinated. However, the brief comment has been widely interpreted to mean that the vaccines provide complete protection against infection or transmission.

In a pandemic that regularly leads to scientific misunderstandings, experts said they sympathized with Dr. Walensky and her obvious desire that Americans continue to take precautionary measures. It was only Monday when she said the rising number of cases left her feeling “impending doom”.

“If Dr. Walensky had said that most people who were vaccinated don’t carry the virus, we wouldn’t be having this discussion,” said John Moore, a virologist at Weill Cornell Medicine in New York.

“What we do know is that the vaccines are very effective against infections – there is more and more data on them – but nothing is 100 percent,” he added. “It is an important public health message that needs to be properly understood.”

Updated

April 1, 2021, 6:59 p.m. ET

A misinterpretation could disrupt the agency’s urgent requests for vaccination, some experts said. By Wednesday, 30 percent of Americans had received at least one dose of vaccine and 17 percent were fully immunized.

“There can be no daylight between what the research shows – really impressive, but incomplete protection – and the description,” said Dr. Peter Bach, director of the Center for Health Policies and Results at Memorial Sloan Kettering Cancer Center in New York.

“This opens the door to the skeptics who believe the government is glossing over science,” said Dr. Bach, “completely undermines any remaining argument as to why people should continue to wear masks after vaccination.”

All coronavirus vaccines spectacularly prevent serious illness and death from Covid-19, but how well they prevent infection is less clear.

Clinical trials with the vaccines should only assess whether the vaccines prevent serious illness and death. The CDC’s research on Monday brought the welcome conclusion that the vaccines are also extremely effective at preventing infection.

3,950 healthcare workers, rescue workers and other people at high risk of infection took part in the study. Participants wiped their noses and sent in samples for testing each week, which allowed federal researchers to track any symptomatic or non-symptomatic infections. Two weeks after vaccination, the vast majority of people vaccinated remained virus-free, the study found.

Follow-up data from clinical studies support this finding. For example, in the results published Wednesday by Pfizer and BioNTech, 77 people who received the vaccine had coronavirus infection compared to 850 people who received a placebo.

“It is clear that some vaccinated people will be infected,” said Dr. Duprex. “We stop the symptoms, we keep people out of hospitals. But we’re not making them completely resistant to infection. “

The number of vaccinated people who become infected is likely to be higher among those who received Johnson & Johnson and AstraZeneca vaccines, which are less effective, experts say. (Still, these vaccines are worth taking because they consistently prevent serious illness and death.)

Infection rates can also be higher in people exposed to a variant of the virus that the immune system can bypass.

Cases across the country are on the upswing again and threaten a new upswing. Dr. Walensky’s comment came just a day after she emotionally urged the American public to continue taking precautionary measures.

“I ask you to hold on just a little longer to get the vaccine if you can, so that all of the people we all love will stay here when this pandemic ends,” she said.

With numbers soaring, it’s especially important that immunized people continue to protect those who have not yet been immunized against the virus, experts say.

“People who have been vaccinated shouldn’t throw away their masks at this point,” said Dr. Moors. “This pandemic is not over yet.”

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Health

Scientists Develop Mouse Embryos in a Mechanical Womb

Scientists Grow Mouse Embryos in a Mechanical Womb

The mouse embryos looked completely normal. All of her organs developed as expected, along with her limbs, as well as the circulatory and nervous systems. Their tiny hearts beat at a normal 170 beats per minute.

But these embryos did not grow in a mother mouse. They were developed in an artificial uterus, the first time such a feat has been accomplished, scientists reported on Wednesday.

The experiments at the Weizmann Institute of Science in Israel should help scientists understand how mammals develop and how gene mutations, nutrients and environmental conditions can affect the fetus. But the work might one day raise profound questions as to whether other animals, even humans, should or could be cultivated outside of a living womb.

In a study published in the journal Nature, Dr. Jacob Hanna, how embryos are removed from the uterus of mice on five days of pregnancy and cultured in an artificial uterus for a further six days.

At this point the embryos were about in the middle of their development; The full gestation is about 20 days. A person at this stage of development would be called a fetus. To date, Dr. Hanna and his colleagues bred more than 1,000 embryos in this way.

“It really is a remarkable achievement,” said Paul Tesar, developmental biologist at Case Western Reserve University’s medical school.

Alexander Meissner, Director for Genome Regulation at the Max Planck Institute for Molecular Genetics in Berlin, said that “it is amazing to get this far” and that the study is “an important milestone”.

However, the research has already gone beyond what investigators described in the paper. In an interview, Dr. Hanna, he and his colleagues took fertilized eggs from the fallopian tubes of female mice immediately after fertilization – on day 0 of development – and bred them in the artificial uterus for 11 days.

Until now, researchers in the laboratory have been able to fertilize mammalian eggs and only breed them for a short time. The embryos needed a living womb. “Placental mammals develop trapped in the uterus,” said Dr. Tesar.

This prevented scientists from answering basic questions about the earliest stages of development.

“The holy grail of developmental biology is understanding how a single cell, a fertilized egg, can create all of the specific cell types in the human body and grow into 40 trillion cells,” said Dr. Tesar. “Researchers have always tried to find ways to answer this question.”

The only way to study the development of tissues and organs was to turn to species like worms, frogs, and flies that do not need a uterus, or to remove embryos from the uterus of laboratory animals at different times for insight into development that are more like snapshots than video.

What was needed was a way to get inside the uterus and watch and optimize mammalian development as it happened. For Dr. For Hanna this meant the development of an artificial uterus.

He spent seven years designing a two-part system that included incubators, nutrients, and a ventilation system. The mouse embryos are placed in glass vials in incubators, where they swim in a special nutrient fluid.

The vials are attached to a wheel that rotates slowly to prevent the embryos from sticking to the wall, where they would deform and die. The incubators are connected to a ventilator that supplies oxygen and carbon dioxide to the embryos and controls the concentration of these gases, as well as the gas pressure and flow rate.

On day 11 of development – more than in the middle of a mouse pregnancy – Dr. Hanna and his colleagues took the embryos, only the size of apple seeds, and compared them with those that developed in the uterus of living mice. The scientists found that the laboratory embryos were identical.

At this point, however, the embryos grown in the laboratory had become too large to survive without a blood supply. They had a placenta and a yolk sac, but the nutrient solution that was diffusing to feed them was no longer enough.

Overcoming this hurdle is the next goal, said Dr. Hanna in an interview. He is considering using a fortified nutrient solution or an artificial blood supply that is attached to the embryo’s placenta.

In the meantime, experiments are due. The ability to keep embryos alive and develop mid-pregnancy “is a gold mine for us,” said Dr. Hanna.

The artificial uterus can allow researchers to learn more about why pregnancies lead to miscarriages or why fertilized eggs cannot be implanted. It opens a new window about how gene mutations or deletions affect the development of the fetus. Researchers may be able to watch individual cells migrate towards their ultimate destinations.

The work is “a breakthrough,” said Magdalena Zernicka-Goetz, professor of biology and biotechnology at Caltech. It “opens the door to a new era in the study of development in the experimental mouse model.”

A recent development offers another possibility. Researchers created mouse embryos directly from mouse fibroblasts – connective tissue cells – to create early embryos without starting with a fertilized egg.

Combine this development with Dr. Hanna’s work and “now you don’t need mice to study mouse embryo development,” said Dr. Meissner. Scientists can potentially make all the embryos they need from connective tissue.

If scientists could make embryos without fertilizing eggs and study their development without a uterus, said Dr. Meissner: “You can escape the destruction of embryos.” It would not be necessary to fertilize mouse eggs in order to destroy them in the course of the study.

But the work could eventually go beyond mice. Two other articles published in Nature on Wednesday report attempts that are close to creating early human embryos in this way. Of course, said Dr. Meissner, the creation of human embryos is years away – if at all allowed. At present, scientists generally fail to examine human embryos after 14 days of fertilization.

In the future, Dr. Tesar: “It is not unreasonable that we might have the ability to develop a human embryo completely outside of the uterus from conception to birth.”

Of course, even the suggestion of this science fiction scenario will horrify many. But it is early days with no certainty that human fetuses could ever develop completely outside of the womb.

Even if they could, Dr. Tesar: “Whether this is appropriate is a question for ethicists, regulators, and society.”

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Health

Some Scientists Query W.H.O. Inquiry Into the Coronavirus Pandemic’s Origins

Some Scientists Question W.H.O. Inquiry Into the Coronavirus Pandemic’s Origins

Asked to respond to the letter, Tarik Jasarevic, a spokesman for WHO, replied in an email that the team of experts that had traveled to China are working on his full report, as well as an accompanying summary report, which we understand will be issued simultaneously in a couple of weeks. “

The open letter indicated that the WHO study was a joint effort by a team of external experts selected by the global health organization and worked with Chinese scientists, and that the team’s report must be agreed upon by all. The letter stressed that the team had been denied access to some records and no laboratories in China were examined.

Updated

March 7, 2021, 3:06 p.m. ET

The team’s letter stated: “While this may be of limited use, it does not represent the official position of the WHO or the result of an unqualified, independent investigation.”

Without naming him, the letter criticized Peter Daszak, an expert on animal diseases and their links to human health, the head of the EcoHealth Alliance. In the letter that began with articles about Dr. Daszak was said to have previously expressed his belief that the virus was most likely to have a natural origin.

Dr. Daszak said the letter’s urge to investigate a laboratory origin for the virus was a position “supported by political agendas”.

“I urge the world community to wait for the WHO mission report to be published,” he added.

Filippa Lentzos, Lecturer in Science and International Security at King’s College London and one of the signatories to the letter, said: “I think to get a credible investigation, it has to be more of a global effort in the EU to feel that there is UN General Assembly should be brought where all the nations of the world are represented and can vote on whether or not to mandate the UN Secretary General to conduct this type of investigation. “

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In Oregon, Scientists Discover a Virus Variant With a Worrying Mutation

In Oregon, Scientists Find a Virus Variant With a Worrying Mutation

Scientists in Oregon have discovered a native version of a fast-spreading variant of the coronavirus that first appeared in the UK – but now combined with a mutation that may make the variant less susceptible to vaccines.

The researchers have only found a single case of this formidable combination to date, but genetic analysis revealed that the variant was community-acquired and did not occur in the patient.

“We didn’t import this from anywhere else in the world – it happened spontaneously,” said Brian O’Roak, a geneticist at Oregon Health and Science University who led the work. He and his colleagues participate in the Centers for Disease Control and Prevention efforts to track variants and have posted their results in databases shared by scientists.

The variant originally identified in the UK, named B.1.1.7, has quickly spread throughout the United States, accounting for at least 2,500 cases in 46 states. This form of the virus is both more contagious and deadly than the original version and is expected to be responsible for most infections in America in a few weeks.

The new version, which surfaced in Oregon, shares the same backbone, but also has a mutation – E484K or “Eek” – seen in variants of the virus circulating in South Africa, Brazil and New York City.

Laboratory studies and clinical studies in South Africa show that the Eek mutation makes current vaccines less effective by weakening the body’s immune response. (The vaccines are still working, but the results are worrying enough that Pfizer-BioNTech and Moderna have started testing new versions of their vaccines to defeat the variant found in South Africa.)

The B.1.1.7 variant with Eek has also appeared in the UK and has been described by scientists as a “worrying variant”. But the virus identified in Oregon appears to have evolved independently, said Dr. O’Roak.

Dr. O’Roak and colleagues found the variant among coronavirus samples collected by the Oregon State Public Health Lab across the state, including some from a health care outbreak. Of the 13 test results they analyzed, 10 turned out to be B.1.1.7 alone and one as a combination.

Other experts said the discovery wasn’t surprising given that the Eek mutation appeared in forms of the virus around the world. However, the occurrence of the mutation in B.1.1.7 is worth seeing, they said.

In the UK, this version of the variant makes up a small number of cases. By the time the combination developed there, B.1.1.7 had already spread across the country.

Updated

March 6, 2021, 10:48 p.m. ET

“We’re at the point where B.1.1.7 is just rolling out in the US,” said Stacia Wyman, a computational genomics expert at the University of California at Berkeley. “As it evolves and slowly becomes the dominant thing, it could accumulate more mutations.”

Viral mutations can reinforce or weaken each other. For example, the variants identified in South Africa and Brazil contain many of the same mutations, including Eek. But the Brazilian version has a mutation, K417N, that is not present in the South African version.

What you need to know about the vaccine rollout

In a study published Thursday in Nature, the researchers compared antibody responses with all three affected variants – those identified in the UK, South Africa and Brazil. In line with other studies, they found that the variant that beat South Africa was the most resistant to antibodies produced by the immune system.

But the variant circulating in Brazil was not as resistant, despite carrying the Eek mutation. “If you have the second mutation, you don’t see such a bad effect,” said Michael Diamond, a viral immunologist at Washington University in St. Louis who led the study.

It is too early to say whether the Oregon variant will behave like it did in South Africa or Brazil. But the idea that other mutations might weaken Eek’s effects is “excellent news,” said Dr. Wyman.

Overall, she said, the finding in Oregon reinforces the need for people to continue taking precautions, such as wearing a mask, until a significant portion of the population is vaccinated.

“People don’t have to freak out, they just have to be vigilant,” she said. “We cannot give up our vigilance as long as these more transferrable variants are still in circulation.”

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Scientists to C.D.C.: Set Air Requirements for Workplaces Now

Scientists to C.D.C.: Set Air Standards for Workplaces Now

Almost a year after scientists showed that the coronavirus can be inhaled in tiny droplets called aerosols that linger in stagnant indoor air, more than a dozen experts are calling on the Biden government to take immediate action to stop the transmission of the virus in the air at high risk limit settings such as meat packing plants and prisons.

The 13 experts – including several who advised President Biden during the transition – urged the administration to mandate a combination of masks and environmental measures such as better ventilation to mitigate the risks in various workplaces.

On Friday, the Centers for Disease Control and Prevention issued new guidelines for reopening schools, but quickly switched to improved ventilation as a precaution. It was only in July that the World Health Organization admitted that the virus could linger in the air in overcrowded indoor spaces after 239 experts publicly urged the organization to do so.

In a letter to the administration, scientists explained detailed evidence of airborne transmission of the virus. It has become even more urgent for the government to take action now, the experts said due to the slow vaccine rollout, the threat of more contagious variants of the virus already circulating in the United States and the high rate of Covid-19 infections and deaths, despite one recent fall in cases.

“It’s time to stop pussy shooting because the virus is mostly airborne,” said Linsey Marr, aerosol expert at Virginia Tech.

“If we properly acknowledge this and implement the right recommendations and guidance, this is our chance to end the pandemic in the next six months,” she added. “If we don’t do that, it could very well drag on.”

The letter was delivered to Jeffrey D. Zients, Coordinator of the Biden Administration’s Covid-19 Response, on Monday. Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention; and Dr. Anthony S. Fauci, Director of the National Institute for Allergies and Infectious Diseases.

The letter urged the CDC to recommend the use of high quality masks such as N95 respirators to protect workers at high risk of infection. At present, health care workers rely mostly on surgical masks, which are not as effective against aerosol transmission of the virus.

Many workers susceptible to infection are black people who have borne the brunt of the epidemic in the United States, the experts noted.

Mr Biden has directed the occupational health and safety agency, which sets workplace requirements, to issue temporary emergency standards for Covid-19 by March 15, including those for ventilation and masks.

However, OSHA will only prescribe standards that are supported by the CDC, said David Michaels, an epidemiologist at George Washington University and one of the signatories.

(Dr. Michaels ran OSHA during the Obama administration; the agency has not had a permanent leader since his departure.)

Updated

Apr 16, 2021 at 10:43 am ET

“Until the CDC makes some changes, OSHA will have difficulty changing the recommendations as it understands that government must be consistent,” said Dr. Michaels. “And CDC has always been considered the lead infectious disease agency.”

Public health authorities, including the WHO, have been slow to recognize the importance of aerosols in the spread of the coronavirus. It wasn’t until October that the CDC realized that the virus could be in the air at times, after an enigmatic series of events where a description of how the virus had spread appeared on the agency’s website, then disappeared, and reappeared two weeks later.

However, the Agency’s recommendations on workplace accommodation did not reflect this change.

At the start of the pandemic, the CDC said health care workers didn’t need N95 respirators and could even wear headscarves to protect themselves. Face coverings were also not recommended for the rest of the population.

The agency has since revised these recommendations. It was recently recommended that you wear two masks or improve the fit of their surgical masks to protect yourself from the virus.

“But they’re not talking about why you need a better fitting mask,” said Dr. Donald Milton, aerosol expert at the University of Maryland. “They recognize the importance of inhaling it and how it is transmitted, yet they don’t say it clearly on their various web pages.”

The agency recommends surgical masks for health care workers and says that N95 respirators are only needed during medical procedures that generate aerosols, such as certain types of surgery.

However, many studies have shown that health care workers who have no direct contact with Covid-19 patients are also at high risk of infection and should wear good quality respirators, said Dr. Celine Gounder, an infectious disease specialist at Bellevue Hospital Center in New York and an advisor to Mr. Biden during the transition.

“The CDC has not emphasized the risk of aerosol transmission enough,” said Dr. Gounder. “Unfortunately, concerns about the offer continue to cloud the discussion.”

Many hospitals still expect their staff to reuse N95 masks as recommended by the agency to reuse when supplies are low. However, since the masks are no longer in short supply, the agency should change its recommendations, said Dr. Gounder.

“We really need to stop this approach of reusing and decontaminating N95,” she added. “We are one year this year and that is really not acceptable.”

At least hospitals are usually well ventilated, so healthcare workers are protected in other ways, the experts said. In meat packers, prisons, buses, or grocery stores where workers have been exposed to the virus for long periods of time, the CDC does not recommend high-quality respiratory equipment or advocate improvements to ventilation.

“When you go to other jobs, that notion that aerosol transfer is important is virtually unknown,” said Dr. Michaels. For example, in food processing plants, a refrigerated environment and lack of fresh air are ideal conditions for the virus to thrive. However, the industry has not taken any safety measures to minimize the risk, he added.

Instead, employers follow the CDC’s recommendations for physical removal and cleaning of surfaces.

The recent emergence of more contagious variants makes it imperative for the CDC to address airborne transmission of the virus, said Dr. Marr from Virginia Tech. Germany, Austria and France are now mandating N95 respirators or other high quality masks in public transport and shops.

Dr. Marr was one of the experts who wrote to WHO last summer asking for airborne transmission recognition. She didn’t expect to be in a similar position again so many months later. She said, “It feels like Groundhog Day.”

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How Scientists Are Making an attempt to Spot New Viruses Earlier than They Trigger Pandemics

How Scientists Are Trying to Spot New Viruses Before They Cause Pandemics

In the summer, Dr. Michael Mina signed a contract with a cold storage company. With many of its restaurant customers closed, the company had freezers available. And Dr. Mina, an epidemiologist at Harvard TH Chan School of Public Health, had half a million vials of plasma made from human blood come to his laboratory from around the country. The samples come from the carefree days in January 2020.

The vials that are now in three huge freezers in front of Dr. Mina’s laboratory are at the center of a pilot project for what he and his staff call the Global Immunological Observatory. You envision an immense surveillance system that can check blood from around the world for the presence of antibodies to hundreds of viruses at the same time. This will give scientists real-time detailed information on how many people have been infected with the virus and how their bodies have responded to the next pandemic.

It could even provide early notification, like a tornado warning. Although this surveillance system cannot directly detect new viruses or variants, it can show when large numbers of people are beginning to gain immunity to a particular type of virus.

The human immune system records the pathogens it has previously hit in the form of antibodies that fight against them and then stay lifelong. By testing for these antibodies, scientists can get a snapshot of what flu viruses you had, which rhinovirus pierced you last fall, even if you had respiratory syncytial virus as a kid. Even if an infection had never made you sick, this diagnostic method called serological tests would detect it.

“We’re all like little recorders,” said Dr. Mina to track viruses without even realizing it.

This type of immune system display is different from a test that looks for an active viral infection. The immune system starts producing antibodies one to two weeks after an infection starts. So the serology is retrospective, looking back at what you caught. Closely related viruses can also produce similar responses, producing antibodies that bind to the same types of viral proteins. This means that carefully designed assays are required, for example to differentiate between different coronaviruses.

But serology reveals things virus testing doesn’t, said Derek Cummings, an epidemiologist at the University of Florida. With a large database of specimens and clinical details, scientists can see patterns in how the immune system reacts in someone without symptoms compared to someone who has difficulty clearing the virus. Serology can also tell before an outbreak begins whether a population has robust immunity to a particular virus or whether it is dangerously low.

“You want to understand what has happened in a population and how well that population is prepared for future attacks from a particular pathogen,” said Dr. Cummings.

The approach could also detect events in the viral ecosystem that would otherwise go unnoticed, said Dr. Cummings. For example, the 2015 Zika outbreak was discovered by doctors in Brazil who noticed a group of babies with unusually small heads who were born seven to nine months after their mothers were infected. “A serological observatory might have picked this up beforehand,” he said.

Serological tests are often small and difficult to perform because they require blood draws from volunteers. For several years now, Dr. Mina and his colleagues came up with the idea of ​​a large and automated monitoring system using sample residue from routine laboratory tests.

“Had we set it up in 2019, when this virus hit the US, we would have had instant access to data that would have enabled us to see it floating around, for example, in New York City without doing anything else,” said Dr. Said Mina.

Updated

Apr. 15, 2021, 5:07 p.m. ET

Although the observatory could not have identified the new coronavirus, it would have detected an abnormally high number of infections from the coronavirus family, including those that cause colds. It may also have shown that the new coronavirus interacted with the patient’s immune system in unexpected ways, causing tell-tale markers in the blood. This would have been a signal to start genetic sequencing of patient samples to identify the culprit, and possibly have provided reasons to close the city earlier, said Dr. Mina. (Similarly, serology would not be able to detect the emergency of a new virus variant, such as the contagious coronavirus variants discovered in South Africa and England, before they spread elsewhere Leave standard genomic sequencing of virus test samples.)

The observatory would require agreements with hospitals, blood banks and other blood sources, as well as a system for obtaining consent from patients and donors. It also faces the problem of funding, noted Alex Greninger, a virologist at the University of Washington. Health insurance companies are unlikely to pay the bill, as serological tests are typically not used by doctors to treat people.

Dr. Mina estimated the observatory would cost about $ 100 million to go live. He pointed out that, according to his calculations, the federal government provided diagnostics company Ellume with more than twice as much to run enough rapid Covid tests to meet American needs for just a handful of days. A pathogen observatory, he said, is like a weather forecasting system based on a variety of buoys and sensors around the world that passively reports events where and when they occur. These systems were funded by government grants and are widely appreciated.

The predictive power of serology is well worth the investment, said Jessica Metcalf, Princeton epidemiologist and member of the observatory team. A few years ago, she and her staff found in a smaller survey that immunity to measles in Madagascar was threateningly low. In fact, there was an outbreak in 2018 that killed more than 10,000 children.

Now the half million plasma samples in Dr. Minas freezers, collected last year by plasma donation company Octopharma at sites across the country, underwent serological testing that focuses on the new coronavirus and is funded with a $ 2 million grant from Open Philanthropy. The tests had to wait for the researchers to set up a new robotic test facility and process the samples. Now they are working on their first batches.

The team hopes to use this data to show how the virus has made its way into the US week after week and how immunity to Covid has grown and changed. They also hope this will spark interest in using serology to shed light on the movement of many more viruses.

“The big idea is to show the world that you don’t have to spend big dollars doing this type of work,” said Dr. Mina. “We should let this happen all the time.”

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U.Ok. Virus Variant Is Most likely Deadlier, Scientists Say

U.K. Virus Variant Is Probably Deadlier, Scientists Say

LONDON – UK government scientists are increasingly realizing that the variant of coronavirus, first discovered in the UK, is more deadly than the original virus. This is a devastating trend that highlights the serious risks of this new phase of the pandemic.

The scientists said last month that there was a “realistic possibility” that the variant would be more deadly. Now a new document states that it is “likely” that the variant is associated with an increased risk of hospitalizations and death.

The UK government has not made the updated results public. These are based on about twice as many studies as their earlier assessment and include more deaths due to Covid-19 cases caused by the new variant B.1.1.7. The document was posted on a government website on Friday and was reviewed at a government advisors meeting the previous day.

The variant is known in 82 countries, including the USA. American scientists recently estimated that it was spreading rapidly there, doubling about every 10 days, and said it could be the dominant version of the virus in the United States by March.

“The calculation of when we can lift restrictions has to be affected,” said Simon Clarke, Associate Professor of Cell Microbiology at the University of Reading, of the new findings. “It provides additional evidence that this variant is more deadly than the one we looked at last time.”

Most Covid-19 cases, including those caused by the new variant, are not fatal. And government scientists relied on studies that looked at a small fraction of the total deaths, making it difficult to determine exactly how much increased risk might be associated with the new variant.

Updated

Apr. 13, 2021 at 10:00 PM ET

However, the strongest studies they relied on estimated that the variant could be 30 to 70 percent more deadly than the original virus.

And the government scientists, who are part of a committee known as the Advisory Group on New and Emerging Respiratory Virus Threats, wrote that the latest studies have helped them control factors like the impact of congested hospitals.

This enabled “increasing confidence in the association” of the new variant “with increased disease severity”.

The variant is thought to be 30 to 50 percent more transmissible than the original virus, although some scientists now believe it is even more contagious. The first sample of it was collected in the south east of England in September and quickly became the dominant version of the virus in the UK. It now accounts for more than 90 percent of cases in many parts of the country.

As it spread, hospitals have been overwhelmed by the pace of new infections. Doctors and nurses treated almost twice as many hospital patients as they did at the height of last year. A strict lockdown has since slashed the number of new coronavirus cases in the UK.

As an example of the growing evidence of the variant’s lethality, government scientists cited a study by the London School of Hygiene and Tropical Medicine. In January, this study looked at the deaths of 2,583 people, 384 of whom are believed to have had cases of Covid-19 caused by the new variant. The study estimated that people infected with the new variant had a 35 percent higher risk of death.

An updated study by the same group relied on 3,382 deaths, of which 1,722 were believed to be from the new variant. This study suggested that the variant could be associated with a 71 percent higher risk of death.

Professor Clarke said the new findings confirmed the UK government’s decision to raise an alert about the variant in December and then release evidence last month that it was potentially more deadly. Some outside scientists initially rejected the warnings.

“You didn’t withhold the data,” said Professor Clarke. “They were very open about how insecure things were.”

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The Coronavirus Is a Grasp of Mixing Its Genome, Worrying Scientists

The Coronavirus Is a Master of Mixing Its Genome, Worrying Scientists

In the past few weeks, scientists have been raising the alarm about new variants of the coronavirus that carry a handful of tiny mutations, some of which appear to make vaccines less effective.

But it’s not just these small genetic changes that are cause for concern. The novel coronavirus tends to mix up large chunks of its genome when making copies of itself. Unlike small mutations, which are like typos in sequence, a phenomenon called recombination is similar to a large copy-and-paste mistake, where the second half of a sentence is completely overwritten with a slightly different version.

A number of new studies suggest that recombination can allow the virus to transform itself in dangerous ways. In the long run, however, this biological machinery could provide a silver lining in helping researchers find drugs that will stop the virus.

“There’s no question that recombination is taking place,” said Nels Elde, an evolutionary geneticist at the University of Utah. “And in fact, it’s probably a little underrated and could even play a role in creating some of the new worrying variants.”

The coronavirus mutations that most people have heard of, like the one in the B.1.351 variant first discovered in South Africa, are changes in a single “letter” of the virus or RNA’s long genetic sequence. Because the virus has a robust system for proofreading its RNA code, these small mutations are relatively rare.

In contrast, recombination is widespread in coronaviruses.

Researchers at Vanderbilt University Medical Center, led by virologist Mark Denison, recently looked at how replication goes wrong in three coronaviruses, including SARS-CoV-2, which causes Covid. The team found all three viruses showed “extensive” recombination when replicated separately in the laboratory.

Scientists fear that recombination could combine different variants of the coronavirus into more dangerous versions in a person’s body. For example, variant B.1.1.7, first discovered in Great Britain, had more than a dozen mutations that appeared suddenly.

Dr. Elde said the recombination may have brought together mutations from different variants that may have arisen spontaneously within the same person over time or that co-infected someone at the same time. At the moment this idea is speculative: “It’s really hard to see these invisible scars from a recombination event.” And while it is possible to get infected with two variants at the same time, this is considered rare.

Katrina Lythgoe, an evolutionary epidemiologist at the Oxford Big Data Institute in the UK, is skeptical that co-infection is common. “But the new worrying variants have taught us that rare events can still have a big impact,” she added.

Recombination may also allow two different coronaviruses from the same taxonomic group to exchange some of their genes. To investigate this risk more closely, Dr. Elde and his colleagues tracked the genetic sequences of many different coronaviruses, including SARS-CoV-2 and some of its distant relatives that are known to infect pigs and cattle.

Using specially developed software, the scientists highlighted the places where the sequences of these viruses aligned and matched – and where they did not. The software suggested that in the last few centuries of virus evolution, many of the recombination events involved segments that made up the spike protein that helps the virus enter human cells. This is worrying, the scientists said, because it could be one way that one virus essentially infects another virus.

“Through this recombination, a virus that cannot infect humans could recombine with a virus like SARS-CoV-2 and take over the sequence for the tip and infect people,” said Stephen Goldstein, an evolutionary virologist who worked on the study.

Updated

Apr. 5, 2021, 8:13 p.m. ET

The results, which were posted online on Thursday but not yet published in a scientific journal, provided new evidence that related coronaviruses are quite promiscuous in terms of recombining with one another. There were also many sequences that appeared in the coronaviruses that seemed to come out of nowhere.

“In some cases, it almost looks like a sequence is coming from space, from coronaviruses that we don’t even know about,” said Dr. Elde. The recombination of coronaviruses across completely different groups has not been studied in detail, also because such experiments may have to be subject to a government review in the USA due to security risks.

Feng Gao, a virologist at Jinan University in Guangzhou, China, said that while the Utah researchers’ new software found unusual sequences in coronaviruses, it does not provide any iron evidence of recombination. It could just be that that’s how they evolved.

“Diversity, no matter how much, doesn’t mean recombination,” said Dr. Gao. “It could well be caused by tremendous diversification during virus development.”

Scientists have limited knowledge of whether new pandemic coronaviruses can arise through recombination, said Vincent Munster, a viral ecologist at the National Institute for Allergies and Infectious Diseases who has been studying coronaviruses for years.

Yet this evidence is growing. In a study published in July and officially published today, Dr. Munster and coworkers suggest that recombination is likely, as both SARS-CoV-2 and the virus behind the original SARS outbreak in 2003 resulted in a version of the spike protein that enables them to skillfully invade human cells. This spike protein binds to a specific entry point in human cells called ACE2. This paper calls for stronger coronavirus surveillance to see if there are others who are using ACE2 and therefore may pose similar threats to humans.

Some scientists are studying recombination machinery not only to ward off the next pandemic, but also to combat it.

For example, Dr. Vanderbilt’s Denison, in his recent study of the recombination of three coronaviruses, found that blocking an enzyme known as nsp14-ExoN in a mouse coronavirus caused a decrease in recombination events. This suggests that the enzyme is critical to the ability of coronaviruses to mix and match their RNA during replication.

Now, Dr. Denison and Sandra Weller, virologist at the University of Connecticut Medical School, asked whether this finding could treat people with Covid.

Certain antiviral drugs, like remdesivir, fight infection by acting as RNA bait that speeds up the viral replication process. But these drugs don’t work as well as some coronaviruses would have hoped. One theory is that the enzyme nsp14-ExoN removes the errors caused by these drugs and thus saves the virus.

Dr. Denison and Dr. Among other things, Weller are looking for drugs that block the activity of nsp14-ExoN and allow remdesivir and other antiviral agents to work more effectively. Dr. Weller compares this approach to cocktail therapies for HIV, which combine molecules that act on different aspects of virus replication. “We need combination therapy for coronavirus,” she said.

Dr. Weller notes that coronaviruses share nsp14-ExoN, so a drug that successfully suppresses it can work against more than just SARS-CoV-2. You and Dr. Denison are still in the early stages of drug discovery and are testing various molecules in cells.

Other scientists see potential in this approach not only to make drugs like remdesivir work better, but also to prevent the virus from correcting one of its replication errors.

“I think it’s a good idea,” said Dr. Goldstein, “because you would drive the virus into what is known as a ‘failure catastrophe’ – basically it would mutate so severely that it is fatal to the virus.”