The Transmissible Lambda Variant is Dominant Strain in Peru


Although news of the delta variant has been front and center, the lambda variant in South America is another strain that public health officials are watching.


This story was originally posted on Infection Control Today.

Scientific researchers continue to try and get a bead on the lambda variant of COVID-19, which initial and—as yet—not peer-reviewed research suggests might possibly be resistant to vaccines. That’s the conclusion reached by investigators with the University of Tokyo, in a study posted on bioRxiv, which has not yet been peer-reviewed. Their conclusions mirror those of a study released several weeks ago—also not peer-reviewed yet—by investigators in Chile.

The study by the University of Tokyo researchers states that two mutations in the lambda variant—T76I and L452Q—makes it more infectious than the variant that had health care systems throughout the world reeling this time last year—D614G, the so-called wild type. (It’s not yet known whether the lambda variant is more infectious than the Delta variant, which in many places in the world, including the United States, is now the dominant variant and also comes with a host of challenges to health care systems.) In addition, states the study, “the RSYLTPGD246-253N mutation, a unique 7-amino-acid deletion mutation in the N-terminal domain of the lambda spike protein, is responsible for evasion from neutralizing antibodies.” The investigators discovered the mutations in lab experiments.

The World Health Organization (WHO) says that the lambda variant—or C.37 variant—has been the COVID-19 carrier in about 81% of infections in Peru since April. The variant was first identified in Peru in August 2020. The WHO declared the lambda variant a variant of interest (VOI) on June 14, a designation that means that it could cause a greater risk than the wild-type variant.

That’s an understatement, according to the investigators at the University of Tokyo, who want the WHO to label the lambda variant a variant of concern (VOC) to put health care systems around the world on notice that this might be their next big challenge. They write that “because the lambda variant is a VOI, it might be considered that this variant is not an ongoing threat compared to the pandemic VOCs. However, because the lambda variant is relatively resistant to the vaccine-induced antisera, it might be possible that this variant is feasible to cause breakthrough infection.”

Kei Sato, PhD, a senior researcher at the University of Tokyo and 1 of the 2 lead authors of the study, tells Reuters that lambda “can be a potential threat to the human society.”

The study states that “since the Lambda variant has dominantly spread according to the increasing frequency of the isolates harboring the RSYLTPGD246-253N mutation, our data suggest that the insertion of the RSYLTPGD246-253N mutation is closely associated with the massive infection spread of the Lambda variant in South America.”

According to data-collecting organization GISAID Initiative, there have been 1037 cases of lambda in the US.

Pablo Tsukayama, PhD, is a molecular microbiologist at Cayetano Heredia University in Lima, Peru, and has been tracking lambda since its appearance. He told Al Jazeera on July 27 that “when we found it, it did not attract much attention. But we continued processing samples, and by March, it was in 50% of the samples in Lima. By April, it was in 80% of the samples in Peru…. That jump from [1%] to 50% is an early indicator of a more transmissible variant.”

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