Lambda vs. Delta COVID Variant: What We Know So Far About the Different Strains

The Delta variant of the coronavirus overwhelmingly remains the dominant strain in the United States, but the Lambda variant has started getting attention in recent days.

Like the Delta variant, Lambda is highly infectious and thought to be more resistant to vaccines than the original version of the virus. Though much remains unknown about the strain, there have been some alarming characteristics detected by researchers.

At the moment, the Lambda variant has been mainly spreading through South America after first being identified in Peru in August 2020, but cases have been seen in Texas and South Carolina. Fewer than 700 cases of the Lambda variant have been sequenced in the U.S. out of more than 34 million coronavirus reported cases, according to one estimate. However, the U.S. has only sequenced a small amount of its cases, so the actual number of cases associated with the strain may be much higher.

In all, 28 countries have identified Lambda variants in COVID cases, according to GISAID. Scientists say it is closely related to one of the earliest known variants of the virus, known as Alpha.

The World Health Organization (WHO) says Lambda has the potential for increased transmissibility and may have increased resistance to neutralizing antibodies, both characteristics associated with the Delta variant.

Even still, studies show vaccines protect against all the major coronavirus strains, including the Delta variant, and researchers believe this to be the case with Lambda. As of now, though, there hasn't been sufficient data regarding exactly how effective current vaccines are against preventing infection from Lambda.

How worried should people be about the Lambda variant? That depends on who you ask. Last month, the WHO classified Lambda as a global "variant of interest," which is considered a level just below a "variant of concern."

"Variants of concern" identified by the organization are the Alpha, Beta, Gamma and Delta.

The WHO's definition for "variant of interest" allows that Lambda has the potential for disease severity and has been identified as causing significant community transmission or multiple COVID-19 infection clusters.

However, on its own separate list regarding variants within the U.S., the Centers for Disease Control and Prevention (CDC) does not include Lambda as being a variant of interest, concern or high consequence.

For now, most researchers remain focused on the Delta variant, which recently accounted for 83 percent of new COVID-19 cases in the U.S. The CDC noted in an internal presentation recently that the "war has changed" against the ongoing pandemic due to the emergence of the highly transmissible Delta variant.

The WHO is also still monitoring other variants, such as Eta, Kappa and Iota. Any of these could develop into a threat, especially considering that earlier in the year Iota spread rapidly in New York City, making up more than a quarter of sequences in the city by February.

But not everyone is ready to dismiss the Lambda variant. Senior researcher Kei Sato of the University of Tokyo recently told Reuters that "Lambda can be a potential threat to the human society."

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The Lambda variant of the coronavirus is causing concern among many. In this file photo, health workers handle a coronavirus test at a drive-thru testing station at Cummings Park on March 23, 2020 in Stamford, Connecticut. John Moore/Getty Images