What Everyone Should Know About the New Lambda COVID-19 Variant

Although it has yet to sweep the U.S. to the same degree as the Delta variant, the latest strain making headlines has been deemed a "variant of interest." Find out what that means and more.

As COVID-19 cases surge across the country due in large part to the highly transmissible, now-dominant Delta (B.1.617.2) variant, health experts continue to closely monitor other potentially threatening variants. One coronavirus strain to be aware of is the Lambda (C. 37) variant, which was first detected in Peru in December 2020. Thus far, genomic sequencing has identified the South American-born strain as the cause of roughly 1,060 COVID-19 cases in the United States, according to GISAID, an independent data-sharing initiative. And while that number arguably pales in comparison to the skyrocketing cases brought on by the Delta strain (which currently accounts for more than 80 percent of cases in the U.S.), Lambda has been classified as a "variant of interest" by the World Health Organization. (FYI — that designation is slightly lower than the Delta's "variant of concern" status.) What's more, it's also currently of particular concern in Texas, one of the biggest COVID-19 hotspots, according to data reported by The New York Times.

Ahead, everything you need to know about the Lambda variant, including how to compares to the Delta variant (and if it can cause breakthrough COVID cases) and answers to questions such as, "is this new strain of COVID more deadly?" (Read more: Why Are the New COVID-19 Strains Spreading More Quickly?)

What Is the COVID-19 Lambda Variant?

If you feel like there's a new COVID-19 variant making headlines every day, you should know that the emergence of new strains is not unique to this virus in particular. In fact, every virus has the ability to change through mutation, and variants (essentially different versions) are to be "expected," especially if a virus continues to spread through communities, according to the Centers for Disease Control and Prevention. And while some strains will pop up and then disappear, others can persist, as evidenced by the global (ongoing) spread of the Delta variant.

The Lambda variant now makes up a majority of COVID-19 cases in Peru where it originated, explains Vivek Cherian, M.D., an internal medicine physician affiliated with the University of Maryland Medical System. It has since spread to other Latin American countries along with the United States, he adds.

How Does the Lambda Variant Differ From the Delta Variant?

Unlike a "variant of concern" such as Delta, Lambda is a considered "variant of interest," which is "a term used when health officials closely monitor a specific variant because mutations possibly can affect the disease severity or transmissibility of that particular strain," explains Dr. Cherian. "The Lambda variant is known to be more resistant to neutralizing antibodies compared to other strains, and there's some evidence to suggest that it could be more infectious and resistant to vaccines." So, while health experts are keeping a very close eye on all known variants of the coronavirus, there have not been enough Lambda variant-caused cases to determine whether the strain has the potential (read: a big enough threat) to be a Delta-level "variant of concern." (

"Relatively speaking, we don't know too much about the Lambda variant at this time," he says. "It certainly seems more transmissible than the original SARS-CoV-2 virus [aka the Alpha variant], but to what degree remains to be seen." This is especially true in the U.S., where the prevalence of the strain is, in Dr. Cherian's words, "minuscule" compared to the dominant Delta variant.

"The data strongly suggests that the Delta variant has higher viral loads and is more contagious compared to the Lambda variant," explains Dr. Cherian. "[And] because the Delta variant is so contagious, it's unlikely the Lambda variant will take over."

How to Protect Yourself Against the Lambda Variant

While Dr. Cherian notes that more research is needed to truly determine the transmissibility of the Lambda variant, one thing is clear: Getting vaccinated remains the best way to protect yourself and others from getting sick. (Yes, breakthrough infections are still possible, but vaccinated patients may experience less severe symptoms or be asymptomatic altogether, according to the CDC.)

And as COVID-19 variants continue to circulate, there is a real threat of new variants emerging that might evade vaccines altogether — a serious problem for everyone, according to Dr. Cherian. "Not getting vaccinated is, of course, an extremely bad thing for unvaccinated individuals, but it could also be a bad thing for people who are vaccinated because you let the virus continue to spread and mutate, and there may eventually become a strain that renders our current vaccines completely ineffective," he cautions.

Before you panic, just know that all the same tools that health experts have been encouraging all along — wearing masks and getting vaccinated, especially— are still effective and are perhaps more important than ever when it comes to squashing the pandemic once and for all. "There is nothing you should be doing differently with regards to protecting yourself from the Lambda variant," says Dr. Cherian. "So far the biggest weapons in our arsenal to win the war against this pandemic are getting fully vaccinated and continuing to wear masks. Bottom line: Get vaccinated."

The information in this story is accurate as of press time. As updates about coronavirus COVID-19 continue to evolve, it's possible that some information and recommendations in this story have changed since initial publication. We encourage you to check in regularly with resources such as the CDC, the WHO, and your local public health department for the most up-to-date data and recommendations.

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