Viruses develop. SARS-CoV-2, the virus that causes Covid-19, is no exception. So the emergence of variants is no surprise, and not every new genetic mutation poses a serious threat.

But in recent weeks a growing drum of news coverage has started to sound the alarm about lambda, a variant first discovered in Peru late last year. The variant, initially known as C.37, quickly spread in parts of South America. On June 14, the World Health Organization classified it as an “interesting variant,” which essentially means that experts suspect it could be more dangerous than the original strain.

The prevalence of lambda and its mutations, which are similar to those found in several other highly contagious or worrying variants, make it worth watching, scientists said. But much remains unknown and it is not yet clear how high the risk is.

“I think part of the interest is just due to the fact that there is a new variant that has a new name,” said Nathaniel Landau, a microbiologist at New York University’s Grossman School of Medicine who studies the new coronavirus variants .

“But I don’t think there is any more cause for concern than before we knew about this variant,” added Dr. Landau added. So far, there is no evidence that Lambda will displace Delta, the highly transmissible variant that now dominates most of the world. “There is no reason to believe that this is now anything worse than Delta.”

Pablo Tsukayama, a microbiologist at Cayetano Heredia University in Peru who documented the creation of lambda, agreed. Latin America has “limited capacity” for genomic surveillance and laboratory follow-up studies of new variants, he said. This has created an information gap that is fueling concerns about lambda. “I don’t think it will be worse than anyone else we already have,” he said. “We know so little that it lends itself to a lot of speculation.”

According to a June 15 update by the WHO, lambda had been reported in 29 countries, territories or areas by mid-June. The variant had been detected in 81 percent of the coronavirus samples sequenced in Peru since April, and 31 percent of them in Chile so far, the agency said.

The variant accounts for less than 1 percent of samples sequenced in the United States, according to GISAID, an archive for viral genomic data. Isolated cases have been reported in some other countries.

The variant contains eight notable mutations, including seven in the gene for the spike protein found on the surface of the virus. Some of these mutations come in other flavors and could make the virus more contagious or help bypass the body’s immune response.

But big questions remain unanswered. It’s not yet clear whether lambda is more transmissible than other variants, whether it causes more serious illnesses, or makes vaccines less effective.


July 11, 2021 at 1:57 p.m. ET

“We don’t have a lot of information compared to the other variants,” says Ricardo Soto-Rifo, a virologist at the University of Chile who studied lambda.

Preliminary laboratory studies that have not yet been published in peer-reviewed journals are cause for concern and reassurance. In these studies, research teams led by Dr. Soto-Rifo and Dr. Landau found that antibodies against Lambda induced by the Pfizer, Moderna and CoronaVac vaccines are less effective than against the original strain, but are still able to neutralize the virus.

The results suggest that these vaccines should still work against lambda, the scientists said. In addition, antibodies aren’t the body’s only defense against the virus; even if they are less strong against lambda, other components of the immune system, such as T cells, can also offer protection.

“This decrease in neutralizing antibodies does not mean that the vaccine is less effective,” said Dr. Soto-Rifo. Real-world studies of how well the vaccines hold up against the variant are still needed, he said.

The researchers also reported that, like several other variants, lambda binds more tightly to cells than the original strain of the virus, making it potentially more transmissible.

Though many questions remain unanswered, Trevor Bedford, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle, said that he doesn’t find lambda as worrying as Delta and doesn’t expect it to become as dominant worldwide.

“Lambda has been around for a while and it has barely made its way into the US, for example, compared to, for example, Gamma” – the variant first identified in Brazil – “which did pretty well here.” He added, “I think it did entire focus should be on Delta. “