As variants of the SARS-CoV-2 virus continue to emerge and spread around the globe, experts have been concerned about how they will affect the efficacy of the vaccines that were designed using the original form of the virus. Two studies published yesterday (May 5), one in The Lancet and one as a letter in the New England Journal of Medicine (NEJM), suggest that the Pfizer-BioNTech vaccine remains highly effective against the B.1.1.7 and B.1.351 variants.  Also, Moderna released a statement indicating that early results from an ongoing study of a booster shot are encouraging with regard to the B.1.351 and P.1 variants as well.

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The researchers behind the study in The Lancet examined thousands of cases in Israel from January through April and found that among those who were fully vaccinated with the Pfizer-BioNTech shots, the vaccine was more than 97% effective at protecting against severe disease a week or more after the second dose. Additionally, as vaccination rates across the country increased, the incidence of COVID-19 decreased. Given that nearly 95% of all COVID-19 cases in Israel this year have been due to the B.1.1.7 variant, according to the authors’ estimate, the success of the Pfizer vaccine shows it works against this variant, which first emerged in the UK in 2020.

“This is really good news,” Annelies Wilder-Smith, an infectious disease researcher at the London School of Hygiene and Tropical Medicine who was not connected to the study, tells The New York Times. “At this point in time we can confidently say that we can use this vaccine, even in the presence of circulating variants of concern.”

In NEJM, the researchers analyzed data from more than 200,000 individuals in Qatar, with estimates that 45% of cases were due to B.1.1.7 and around 50% were caused by the SARS-CoV-2 variant B.1.351, which first emerged in South Africa. Those who were fully vaccinated (here defined as 14 days after the second dose) had roughly 90% protection against severe disease with B.1.351 and B.1.1.7, which has been suspected of being more transmissible and more deadly. The protection against infection with B.1.351 was around 75%.

“We should expect a degree of reduction in protection against B.1.351, but not to the extent we should be freaking out about it,” microbiologist John Moore of Weill Cornell Medicine who was not involved in the study, tells The Washington Post.

In the statement distributed yesterday, Moderna CEO Stéphane Bancel discussed an ongoing Phase 2 study meant to assess protection against the variants B.1.351 and P.1 (which originated in Brazil) through a third shot of either a half dose of the standard COVID-19 vaccine or a booster designed with B.1.351 in mind. Forty participants who had been fully vaccinated six to eight months prior were given one of the booster shots, and 15 days later, everyone in the trial had levels of antibodies against the variants and the initially dominant type of the virus that exceeded levels typically following primary vaccination, CNN reports.