Moderna announced today (January 25) plans for testing two different booster vaccines aimed at the SARS-CoV-2 variant B.1.351, also known as 501Y.V2, that emerged in South Africa and has now spread to numerous countries.
“The virus is changing its stripes, and we will change to make sure we can beat the virus where it’s going,” Stephen Hoge, the president of Moderna, tells The Washington Post.
A study from Moderna posted to the preprint server bioRxiv today that has not yet been peer-reviewed reports that its vaccine produced neutralizing antibodies against several SARS-CoV-2 variants, including B.1.351 and B.1.1.7, the latter of which was first spotted in the UK and is rapidly becoming common in other countries. But antibody levels produced in response to B.1.351 were about six times lower than prior variants. Moderna’s statement says that these antibody titers “remain above levels that are expected to be protective,” but warns that “these lower titers may suggest a potential risk of earlier waning of immunity to the new B.1.351 strains.”
The Moderna vaccine is currently administered as two doses spaced a month apart. According to the statement, the company will test whether a third shot of the current vaccine or a strain-specific booster shot will enhance immunity to B.1.351.
“Out of an abundance of caution and leveraging the flexibility of our mRNA platform, we are advancing an emerging variant booster candidate against the variant first identified in the Republic of South Africa into the clinic to determine if it will be more effective to boost titers against this and potentially future variants,” says Stéphane Bancel, the chief executive officer of Moderna, in the statement.
B.1.351, first detected in South Africa in October 2020, is one of a growing number of SARS-CoV-2 variants. This one is distinct from the highly transmissible B.1.1.7, although both versions have multiple mutations on the spike protein, which the virus uses to enter cells. According to the US Centers for Disease Control and Prevention, there is no evidence that B.1.135 causes more severe disease than other variants do.