How worried should we be about the Lambda variant?

In June this year, the World Health Organization added another variant of SARS-CoV-2 to its watch list as a variant of interest. Called Lambda, the variant first appeared in Peru in late 2020 and now makes up the majority of the cases sequenced there.

Last week, Kei Sato at the University of Tokyo published a preprint on server bioRxiv (DOI: 10.1101/2021.07.28.454085 ). The results of lab-based studies presented suggest that Lambda is comparable to or a little less infective than the Delta variant that currently dominates US cases, and that, compared with the original form of the virus, several mutations in the spike protein reduce the performance of the vaccine-induced neutralizing antibodies by half. In an email, Sato told C&EN that doesn’t mean vaccines are useless, just that neutralization is affected: In practice, vaccinated people have a broad antibody response to multiple parts of the spike protein, as well as protection from other parts of the immune system. Other variants have shown similar reductions in neutralizing antibodies’ effectiveness but vaccines still protect most people against illness caused by these variants.

Marco Binder, a virologist at the German Cancer Research Center, says he’s not panicked and points to another preprint suggesting vaccines will still neutralize or control infection (bioRxiv 2021 DOI: 10.1101/2021.07.02.450959v1). Both these studies still need to undergo peer review.

Binder says in his opinion, Lambda is not a game-changer for Europe and the US in the same way that the Delta variant was. “I have a hard time imagining a variant that could displace Delta as easily as Delta replaced Alpha,” he says. The variant has taken its toll in Peru and other South American countries where Delta is less prevalent.

Pablo Tsukayama at Cayetano Heredia University is part of the genomic surveillance efforts in Peru. He says that while the country only has capacity to sequence around 0.1% of all cases, Lambda is now stabilizing at around 80% of all cases they sequence. The rapid growth since late March, he says, is “strong evidence of more transmissibility” that needs to be backed up with robust evidence from laboratory and epidemiological studies. While the Lambda variant has been spreading in South America for a while, he says no one was really paying attention for a long time. He describes the new preprints coming out as a start, but cautions that they each use different methods and populations. “We still know very little”, he says, but there is “no reason to believe it will be worse than Delta.”