As worldwide Covid-19 deaths surpass four million, an emerging variant of the coronavirus, called lambda, has been labeled a "variant of interest" by the World Health Organization (WHO)—and early research suggests it could be more transmissible and vaccine-resistant than the original coronavirus strain.

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What is the lambda variant?

The lambda variant was first identified in Peru in December 2020, Quartz reports, and in that country it accounted for 81% of cases between mid-April and mid-June. Since it was identified, the variant has been spotted in more than 24 countries, including several nations in Latin America—including Argentina, Chile, and Ecuador—as well as the United States and Britain.

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According to a preprint study published in BioRxiv, the lambda variant has novel mutations on the receptor binding domain of the virus's spike protein, which may make it more transmissible and more resistant to vaccines.

Specifically, according to the study, the variant had a roughly three-fold increase in resistance to neutralizing antibodies elicited by the Covid-19 vaccine developed by Pfizer-BioNTech, and a 2.3-fold increase in resistance to antibodies elicited by the Moderna vaccine. And a separate study, published in MedRxiv, found the lambda variant had a 3.05-fold increase in resistance to antibodies elicited by the CoronaVac vaccine.

But the good news, according to researchers, is that current vaccines prompt such a strong antibody response that they should remain highly effective in preventing real-world infections.

Nathaniel Landau, a virologist at NYU Grossman School of Medicine and co-author of the preprint BioRxiv study, emphasized that antibodies produced by Covid-19 vaccines still were effective against the lambda variant, as they are against all coronavirus variants identified so far. "The results we see are very similar for all these variants," Landau said. "We're primarily looking at the mRNA vaccines, and vaccine-elicited antibodies do a good job of neutralizing all the variants."

Peter Hotez, from the Baylor College of Medicine, said in a tweet the BioRxiv study suggests the "good news is that mRNA vaccines still look good," but he added that the findings serve as a reminder to "accelerate vaccinating the Southern Hemisphere, Latin America, Africa, [Southeast] Asia ASAP."

A 'variant of interest'

On June 14, WHO labeled the lambda variant as a "variant of interest," a categorization a step below "variant of concern." However, for his part, Landau said currently available evidence suggests the lambda variant could eventually become a variant of concern.

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Meanwhile, Britain on June 23 labeled the variant a "variant under investigation," citing its "international expansion" as well as its "novel combination of mutations." According to MedPage Today, CDC has not yet listed the variant on its variant tracker.

Worldwide Covid-19 deaths surpass 4M

Concerns about the lambda variant are rising as the worldwide Covid-19 death toll surpassed four million on Thursday, according to the Center for Systems Science and Engineering at Johns Hopkins University.

Tedros Adhanom Ghebreyesus, director-general of WHO, said the death toll is continuing to rise in large part due to emerging variants and inequities in vaccine distribution. "Compounded by fast-moving variants and shocking inequity in vaccination, far too many countries in every region of the world are seeing sharp spikes in cases and hospitalizations," he said.

He cautioned that unless vaccines are distributed more equitably on a global scale, new, potentially more dangerous variants of the coronavirus would continue to form.

"Vaccine nationalism, where a handful of nations have taken the lion's share, is morally indefensible and an ineffective public health strategy against a respiratory virus that is mutating quickly and becoming increasingly effective at moving from human-to-human," Tedros said. "At this stage in the pandemic, the fact that millions of health and care workers have still not been vaccinated is abhorrent."

Maria Van Kerkhove, who works on coronavirus response with WHO, added that there are "more than two dozen countries that have epidemic curves that are almost vertical," with the virus rapidly spreading in areas with low vaccination rates. "The virus is showing us right now that it's thriving," she said.

According to the New York Times, it took nine months to reach one million worldwide Covid-19 deaths but just 3.5 months to reach two million, three months to reach three million, and about 2.5 months to reach four million. And according to experts, those figures are just the officially reported numbers, which likely undercount the actual total of Covid-related deaths.

Citing the number of excess deaths reported around the world, Jennifer Nuzzo, an epidemiologist at Johns Hopkins' Bloomberg School of Public Health, said, "The numbers may not tell the complete story," particularly in lower-income nations hard-hit by the pandemic. (Sullivan, The Hill, 7/7; Fiore, MedPage Today, 7/7; Slotnik, New York Times, 7/8; Kapur/Lahiri, Quartz, 7/8)