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Should You Worry About the Lambda Variant?

A pharmacy advertises the Covid-19 vaccine

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Key Takeaways

  • The WHO designated the Lambda variant as a variant of interest (VOI) in June.
  • The Lambda variant was first detected in Peru, and now accounts for about 700 cases in the United States.
  • Experts say Lambda is less worrisome than the Delta variant, and that people should continue to follow their area’s masking and social distancing protocols.

The Lambda variant has been detected in about 700 COVID-19 cases in the United States. Experts say Lambda is less worrisome than the Delta variant, but that people should continue to follow their area’s masking and social distancing protocols regardless of which variant is circulating.

The Lambda variant was first detected in Peru in December 2020 and has since been identified in 29 countries.

In June 2021, the World Health Organization (WHO) designated Lambda as a variant of interest (VOI). WHO defines VOIs as variants that “cause significant community transmission or multiple COVID-19 clusters.” These are less threatening than variants of concern (VOC) and variants of high consequence (VOHC).

The Delta variant is classified as a VOC. Currently, there are no variants classified as VOHCs. The Centers for Disease Control and Prevention (CDC) has not yet updated its COVID-19 variant pages to include Lambda.

When evaluating case numbers and public health risks associated with variants, experts suggest to be most cautious about the Delta variant.

Tom Kenyon, MD, MPH, chief health officer at Project HOPE and former director of global health at the CDC, says that the Delta variant has led to an “explosive situation” of COVID-19 cases. As a result, he urges people to combine multiple layers of protection, like getting vaccinated and following social distancing measures.“

"During this period of uncertainty, when the Delta variant is creating a new wave of infections and when we know our vaccines are very effective but not perfect, the vaccinated should also be masking up when they are indoors with people who are unvaccinated or have unknown vaccination status,” Kenyon tells Verywell in an email. “COVID-19 is far from over.”

Janice Johnston, MD, chief medical director and co-founder of Redirect Health, says that the concern with Lambda is the same with all variants—that as the virus mutates, it can become more transmissible and can be capable of creating more severe diseases.

“The Lambda is present in the U.S., but it's not to the degree that the Delta has presented itself in the country,” Johnston tells Verywell. “Primarily, it's Delta that we're seeing and that we're concerned about.” 

The virus can mutate so long as it has a host in unvaccinated individuals, she adds.

Experts say it’s no secret that variants are complicating the pandemic. The Delta variant now accounts for more than 80% of cases in the United States. It prompted some cities to return to indoor mask mandates and social distancing measures. In unvaccinated hotspots like Arkansas, case rates are on the rise.

Jonathan Baktari, MD, CEO of e7health, says that administering a booster vaccine or formulating a variant-specific vaccine could be productive next steps.

“There's hardly any vaccines I can think of that are single dose,” Baktari tells Verywell. “What the vaccine world knew prior to COVID [is] that you generally needed a booster to get the immune system to rev up the machinery to make more antibodies.”

He says that in addition to asking the CDC for permission to release a booster shot of the same technology, both Moderna and Pfizer are working on a trivalent vaccine to cover three strains of the coronavirus: the original, Lambda, and Delta.

Recent studies showed that the vaccines are effective against variants, albeit to different degrees. A recent preprint study suggested that the Johnson & Johnson vaccine was less effective against the Delta variant than the mRNA vaccines in preventing infection.

“We're all going to learn the Greek alphabet going through this pandemic as a new [variant] pops up,” Johnston says. “It's going to be important to follow these studies to see what's the best mechanism to look at. Do we need to make some tweaking or can we continue just to look at a booster shot?”

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

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  1. World Health Organization. Tracking SARS-CoV-2 variants. Updated July 23, 2021.

  2. Tada T, Zhou H, Samanovic MI, et al. Comparison of neutralizing antibody titers elicited by mrna and adenoviral vector vaccine against sars-cov-2 variantsbioRxiv. Published online July 21, 2021:2021.07.19.452771. doi: 10.1101/2021.07.19.452771