To study the impact of the Moderna vaccine, called mRNA-1273, the company took blood samples from eight people who had received two doses of the vaccine, and from primates that had also been immunized.
While the current two-dose regimen is holding so far, it's less effective against a South African variant-which has the company exploring a third shot and a variant-specific booster.
The race against COVID-19 has become more urgent as new, potentially more contagious variants emerge.
Moderna, which carried out the studies with the National Institutes of Health, has submitted the study to a preprint server so it can be analyzed by the wider scientific community.
The Transportation Security Administration is expected this week to issue a separate security directive related to masks, people briefed on the matter said.
"As we seek to defeat the COVID-19 virus, which has created a worldwide pandemic, we believe it is imperative to be proactive as the virus evolves".
Moderna CEO Stephane Bancel said the move was out of "an abundance of caution" after preliminary lab tests suggested its shot produced a weaker immune response to that variant. Maharashtra has recorded 2,697 new cases while Karnataka registered 902 new cases yesterday.
But the reassuring news that vaccine-elicited antibodies remained effective against concerning new variants was tempered by an ominous finding.
South Africa's 501Y.V2 variant is 50% more infectious than the regular strain and has been detected in at least 20 countries.
The CDC has asserted the spread of the U.K. -originated strain has the potential to increase the United States' pandemic trajectory in the coming months, potentially leading to more infections, exacerbating the burden on an already strained health care system and causing more deaths. "Higher vaccination coverage might need to be achieved to protect the public".
The South African mutant virus shares some mutations with the United Kingdom variant.
In the second part of the company's plan, it's developing a new booster vaccine candidate that it will put into a Phase 1 study in the USA, "to evaluate the immunological benefit of boosting with strain-specific spike proteins". He says he is especially concerned about the South African variant, which he describes as "different and more ominous than the one in the United Kingdom".