But big questions remain unanswered. It is not yet clear whether Lambda is more transmissible than other variants, whether it causes more severe disease or whether it renders vaccines less effective.
“We don’t have a lot of information, compared to the other variants,” said Ricardo Soto-Rifo, a virologist at the University of Chile who has studied Lambda.
Preliminary laboratory studies, which have not yet been published in peer-reviewed journals, provide reason for both concern and reassurance. In these studies, research teams led by Dr. Soto-Rifo and Dr. Landau found that antibodies induced by the Pfizer, Moderna and CoronaVac vaccines are less powerful against Lambda than against the original strain, but that they are still able to neutralize the virus.
The findings suggest that these vaccines should still work against Lambda, the scientists said. Moreover, antibodies are not the body’s only defense against the virus; even if they’re less potent against Lambda, other components of the immune system, like T cells, may also provide protection.
“This decrease in the neutralizing antibodies does not mean that the vaccine has decreased effectiveness,” Dr. Soto-Rifo said. 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 does, which may make it more transmissible.
Although many questions remain, Trevor Bedford, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle, said that he does not find Lambda as worrisome as Delta and does not expect it to become as dominant globally.