While some breakthrough cases in people fully vaccinated against Covid-19 are inevitable, they are unlikely to result in hospitalization or death. But an important question about breakthrough infection remains unanswered: Can the vaccinated develop a so-called long covid?

Long Covid refers to a range of symptoms – such as severe fatigue, brain fog, headache, muscle aches, and trouble sleeping – that can last for weeks or months after the active infection has ended. The syndrome is little known, but studies suggest that between 10 and 30 percent of adults who contract the virus can have Covid for a long time, including those who had mild illness or no symptoms at all.

But the vast majority of the long-term data collected by Covid concerns the unvaccinated population. The risk of developing long-term Covid has not been studied in fully vaccinated people who become infected after vaccination.

While preliminary research suggests that it is indeed possible that a breakthrough case could lead to symptoms that could last weeks to months, there are still more questions than answers. What percentage of breakthrough cases result in persistent symptoms? How many of these people are recovering? Are the persistent symptoms after a breakthrough infection as severe as with the unvaccinated?

“I just don’t think there’s enough data,” said Dr. Zijian Chen, medical director of the Center for Post-Covid Care at Mount Sinai Health System in New York. “It’s too early to say that. The number of people who get sick after vaccination is not that high right now, and there is no good tracking mechanism for these patients. “

A study of Israeli health workers recently published in the New England Journal of Medicine offers insight into the risk of long-term Covid infection after a breakthrough infection. Of 1,497 fully vaccinated health care workers, 39 – approximately 2.6 percent – developed breakthrough infections. (All workers were thought to be infected after contact with an unvaccinated person, and the study was conducted before the delta variant became dominant.)

While most breakthrough cases were mild or asymptomatic, seven out of 36 workers observed after six weeks (19 percent) still had persistent symptoms. These long Covid symptoms included a mixture of persistent loss of smell, persistent cough, fatigue, weakness, shortness of breath, or muscle pain.

However, the study’s authors caution against drawing too many conclusions from the research. The sample size – only seven patients – is small. And the research is designed to look at antibody levels in those infected, said Dr. Gili Regev-Yochay, Director of the Department of Epidemiology of Infectious Diseases at Sheba Medical Center. It was not designed to study the risk of long-term Covid illness after a breakthrough infection.

“That was not the scope of this paper,” said Dr. Regev-Yochay. “I don’t think we have an answer to that.”

Still, the fact that one in five healthcare workers who had a breakthrough infection still had persistent symptoms after six weeks seems to be the first clue from a peer-reviewed study that long Covid is possible after a breakthrough infection.

Updated

Aug 16, 2021, 1:10 p.m. ET

“People said to me, ‘You are fully vaccinated. Why are you so careful? ‘”Said Dr. Robert M. Wachter, professor and chair of the medical school at the University of California at San Francisco. “I’m still in the camp that I don’t want to get Covid. I don’t want to get a breakthrough infection. “

Dr. Wachter said that despite the many limitations of the Israeli study, the data provides more evidence that those vaccinated should continue to take reasonable precautions to avoid the virus.

“I’ll take it at face value that one in five people continued to feel bad six weeks after a breakthrough,” said Dr. Guardian. “That’s enough to wear two masks when you go shopping in the supermarket, which isn’t that stressful anyway.”

Understand the state of vaccination and masking requirements in the United States

    • Mask rules. The Centers for Disease Control and Prevention in July recommended that all Americans, regardless of vaccination status, wear masks in public places indoors in areas with outbreaks, reversing the guidelines offered in May. See where the CDC guidelines would apply and where states have implemented their own mask guidelines. The battle over masks is controversial in some states, with some local leaders defying state bans.
    • Vaccination regulations. . . and B.Factories. Private companies are increasingly demanding coronavirus vaccines for employees with different approaches. Such mandates are legally permissible and have been confirmed in legal challenges.
    • College and Universities. More than 400 colleges and universities require a vaccination against Covid-19. Almost all of them are in states that voted for President Biden.
    • schools. On August 11, California announced that teachers and staff at both public and private schools would have to get vaccinated or have regular tests, the first state in the nation to do so. A survey published in August found that many American parents of school-age children are against mandatory vaccines for students but are more likely to support masking requirements for students, teachers and staff who are not vaccinated.
    • Hospitals and medical centers. Many hospitals and large health systems require their employees to have a Covid-19 vaccine, due to rising case numbers due to the Delta variant and persistently low vaccination rates in their communities, even within their workforce.
    • new York. On August 3, New York City Mayor Bill de Blasio announced that workers and customers would be required to provide proof of vaccination when dining indoors, gyms, performances, and other indoor situations. City hospital staff must also be vaccinated or have weekly tests. Similar rules apply to employees in New York State.
    • At the federal level. The Pentagon announced that it would make coronavirus vaccinations compulsory for the country’s 1.3 million active soldiers “by mid-September at the latest. President Biden announced that all civil federal employees would need to be vaccinated against the coronavirus or undergo regular tests, social distancing, mask requirements and travel restrictions.

Making breakthrough infection research difficult is the fact that the U.S. Centers for Disease Control and Prevention only track post-vaccination infections that result in hospitalization or death. While the CDC continues to study breakthrough infections in several large cohorts, the lack of data on all breakthrough cases remains a source of frustration among scientists and patient organizations.

“It is very frustrating not to have data at this point in the pandemic to know what will happen to breakthrough cases,” said Akiko Iwasaki, an immunologist at Yale School of Medicine who conducts studies on long-term Covid. “When a mild breakthrough infection turns into a long Covid, we don’t have that number under control.”

Diana Berrent, founder of Survivor Corps, a Facebook group for people affected by Covid-19 with approximately 171,000 members, conducted an informal survey and found 24 people who said they had persistent symptoms after a breakthrough infection. It is not a scientific sample and the cases have not been validated, but the survey shows that more data is needed on breakthrough cases, Ms Berrent said.

“You can’t extrapolate it to the general population, but it sends a very strong signal that the CDC must mandate coverage of every breakthrough case,” Ms. Berrent said. “We can’t know what we’re not counting.”

However, some experts predict that the surge in new cases caused by the spread of the Delta variant will unfortunately lead to more groundbreaking cases in the coming months. Dr. Chen of Mount Sinai said it would take several months to enroll patients with long covid due to a breakthrough infection.

“We are waiting for these patients to show up at our door,” said Dr. Chen.

Despite the lack of data, one thing is clear: vaccination reduces the risk of getting infected and developing Covid, Athena Akrami, a neuroscientist at University College London, said the data from nearly 4,000 long-term Covid patients developed after long Covid collected and released after a battle with Covid-19 in March 2020.

“It’s simple math,” said Dr. Akrami. “If you reduce infections, the likelihood of long-term Covid illnesses automatically decreases.”