While the Delta variant has become the dominant strain of the coronavirus in the U.S.—responsible for more than 93 percent of circulating cases—a different variant has swept much of South America.
The Lambda variant, also known as C.37, was first detected in Peru in August 2020 and has since spread to other countries, many in Latin America.
According to the World Health Organization (WHO)’s mid-June report, the variant has now been detected in 29 countries, territories or areas, including the U.S., the U.K., Canada, Brazil, Colombia, Ecuador, France, Spain, Chile and Argentina, among others.
The exact origins of the Lambda variant remain unclear, but scientists say the Andean strain emerged in South America. Since its rapid transmission, Lambda now represents more than 90 percent of the COVID-19 cases in Peru. Comparably, the strain had only accounted for 0.5 percent of cases in December.
Peruvian health officials have suggested that the variant caused the country’s infections to surge in a second wave during the spring.
Researchers who have documented the emergence of the mutation said Lambda did not attract much attention when it was first discovered, but the variant’s rapid spread has captured the interest of various experts.
“We continued processing samples, and by March, it was in 50 percent of the samples in Lima. By April, it was in 80 percent of the samples in Peru,” Pablo Tsukayama, an assistant professor in molecular microbiology at Cayetano Heredia University in Lima, told Al Jazeera. “That jump from 1 to 50 percent is an early indicator of a more transmissible variant.”
On June 14, the WHO designated the strain as a “variant of interest.”
Highly contagious variants have presented new, more challenging obstacles for health officials trying to contain the virus.
While vaccines have proved to be fairly effective against new strains, mutations of the original coronavirus have been shown to result in more severe illness for healthy individuals who hadn’t previously been hospitalized and a greater number of breakthrough cases—although the majority of vaccinated people who have become infected have not required hospital care.
The Delta variant’s transmissibility has caused concerns that the Lambda variant could only exacerbate the surges recently seen in states like Florida, Arkansas, Louisiana and Mississippi.
Last month, a Texas hospital reported its first case of the Lambda sequence. Days later, Florida reported that more than 100 cumulative confirmed cases of the strain.
But some researchers have suggested that Lambda may not dominate the U.S. in the same way it has devastated many countries in South America.
“It’s survival of the fittest,” Dr. Anna Durbin, a professor in the Department of International Health at the Johns Hopkins Bloomberg School of Public Health, previously told Newsweek.
She continued, “You have these viruses that replicate and they get mutations. The one that can replicate for the highest titer or be transmitted better is the one that’s going to survive because that one is going to spread more easily and the other variants are going to sort of just die out.”
When it comes to Lambda and Delta, Durbin said: “They both have advantages in terms of transmissibility and I don’t think that the lambda variant could out compete the Delta variant.”
It is unclear if the Lambda variant may undergo further mutations that may make it stronger than the Delta variant, but the strain is continuing to spread globally.
Over the weekend, Japan confirmed its first case of the Lambda sequence after an infected person arrived to the country from Peru earlier in July. The Japanese Ministry of Health stated that an asymptomatic woman tested positive at an airport’s quarantine check three days before the opening ceremony of the summer Olympics.