(CNN) As the coronavirus pandemic continues, infections caused by the Lambda variant have been emerging in the United States, including in Texas, where Houston Methodist Hospital last month reported its first case.
Genomic sequencing has identified 1,060 cases of Covid-19 caused by the Lambda variant in the United States so far, according to the independent data-sharing initiative GISAID. While that number is a far cry from the surge in cases caused by the Delta variant -- representing about 83% of new cases in the US -- infectious disease experts have said that Lambda is a variant they are watching closely.
The Lambda variant was first identified in Peru in December. The World Health Organization designates Delta as a "variant of concern." Lambda is designated a degree lower as a "variant of interest."
"I think any time a variant is identified and demonstrates the capacity to rapidly spread in a population, you have to be concerned," Dr. Gregory Poland, a professor of medicine and director of the Vaccine Research Group at the Mayo Clinic in Rochester, Minnesota, told CNN on Friday.
"There are variants arising every day -- if a variant can be defined as new mutations," he said. "The question is, do those mutations give the virus some sort of advantage, which of course is to human disadvantage? The answer in Lambda is yes."
There is a lot left to learn about Lambda.
The variant is not nearly as worrisome as the Delta variant in the US, which has been driving a rise in cases nationwide, but early studies suggest that it has mutations that make it more transmissible than the original strain of the coronavirus.
"Lambda has mutations that are concerning but this variant remains quite rare in the US despite being around for several months," Dr. Preeti Malani, chief health officer in the division of infectious diseases at the University of Michigan in Ann Arbor, wrote in an email on Friday.
"It's difficult to know for certain how transmissible Lambda is and how well vaccines work. So far, it seems that Lambda is more transmissible than the original SARS-CoV-2 virus," which is similar to Delta and other variants, wrote Malani, an expert with the Infectious Diseases Society of America. SARS-CoV-2 is the name of the coronavirus that causes Covid-19.
"Thankfully studies suggest that the currently available vaccines remain protective. We have learned during the pandemic that things can change quickly, so controlling spread of COVID-19 in general will help manage Lambda," Malani wrote. "As long as there is uncontrolled spread of SARS-CoV-2, we will see more variants in the future. The only way out is widespread vaccination to control spread and prevent further mutation of SARS-CoV-2. It's a race between getting enough of the world vaccinated and the development of new variants that are less responsive to counter measures."
So far, data remain split on how well vaccines protect against the Lambda variant, and scientists say they need to study this more.
In July, researchers wrote in a lab study that they found some evidence that people who got the single-dose Johnson & Johnson Covid-19 vaccine might benefit from a booster dose to better protect them from new variants of the coronavirus, including the Lambda variant. The study was done in the lab and does not reflect real-world effects of the vaccine -- and it's published online as a preprint to the server biorxiv.org, meaning it was not subject to careful peer review.
Nathaniel Landau of the New York University Grossman School of Medicine and colleagues said their tests of blood taken from vaccinated volunteers shows that at least some of the newly emerging variants may evade the protection offered by a single dose of Johnson & Johnson's Janssen vaccine. A boost of a second dose of J&J vaccine, or even with Moderna's or Pfizer's, might help, the researchers reported.
In the study, the variants Beta, Delta, Delta plus and Lambda showed only "modest" resistance against antibodies elicited by the Pfizer/BioNTech and Moderna coronavirus vaccines, suggesting the vaccines still work.
A separate pre-print paper, posted last week to the online server biorxiv.org, found in lab experiments that three mutations -- called the RSYLTPGD246-253N, 260 L452Q and F490S -- found in the spike protein of the Lambda variant may confer resistance to immunity induced by vaccines, but more research is needed. The paper, authored by scientists in Japan, has not been published yet in a peer-reviewed journal.
"Two additional mutations, T76I and L452Q, help make Lambda highly infectious. Currently, the Lambda variant has been flagged as a 'Variant of Interest' by the WHO. We do not know yet whether this variant is more concerning than the Delta variant," pharmacist and epidemiologists Dr. Ravina Kullar, who is an expert with the Infectious Diseases Society of America, wrote in an email on Friday.
"There needs to be extensive genomic surveillance studies that are done to assess how the vaccines' efficacy is affected by the Lambda variant," Kullar wrote. Until Covid-19 cases overall decrease, "the best way to prevent the emergence of more variants is getting fully vaccinated, not traveling internationally, and following strict infection prevention measures including wearing a face mask, physically distancing from others, and not attending large social gatherings."
Vaccines are vital to counter new coronavirus variants, such as Lambda, which might remain rare in the US but is associated with "substantive rates of community transmission in multiple" countries in the region, according to the WHO.
Overall, Poland, the Mayo Clinic professor, warned that the more people don't wear masks and remain unvaccinated, the more likely additional variants will emerge in the future -- including one that might evade vaccines completely. Because as the coronavirus continues to jump from person to person, with each new infection, it changes a little bit -- just like any virus does -- and those changes or mutations could either be benign, or make it more easily transmissible and dangerous.
Poland called it playing "Russian roulette" to allow a virus to spread freely with no mitigations, such as wearing masks or getting vaccinated.
"We will continue to develop more and more variants, and eventually, one or more of these variants will learn how to evade vaccine-induced immunity," Poland said. "And if that's true, we will start all over again."