mRNA Vaccine Booster Shots Likely Required Within Six Months To Protect Against Covid-19 Variants

The majority of new infections in the US, Europe, and most other countries are now driven by variants. Until recently, the B.1.1.7 variant was the most dominant strain in the UK and throughout Europe and is prevalent in the United States as well. In South Africa the dominant strain is the B.1.351 variant; in South America, the P.1 variant. Now in India, three closely related strains, B.1.617.1, B.1.617.2, and B.1.617.3, are now running rampant. The B.1.617.2 variant has appeared in the UK as well. These variants of SARS-CoV-2 are highly transmissible, capable of reinfection, and cause more serious disease. They also introduce the distressing possibility that current generations of Covid-19 vaccines may not protect as well against these variants as they do original strains.

A new preprint study conducted by Moderna describes both the hope and challenge of booster vaccines as an approach to the solution to the problem of variants. Their booster shots appear to be effective at neutralizing at least two of the new variants, B.1.351 and P.1. But importantly, their preprint study also revealed the first-generation Moderna vaccine doesn’t protect against the variants for as long as we initially hoped.

The phase II study compared the efficacy of two different additions to the existing two-dose regimen: half a dose more of the vaccine developed based on the original strain, or a full dose of a new vaccine based on the B.1.351 variant first detected in South Africa. (A version that combines the two is also in the works, though the data has yet to be released.) Using lab-grown virus, the researchers found that both approaches raised neutralizing antibody levels to impressive new heights (see Figure 1C). No indication was given as to when these boosters might be available to the general public, but it is probably safe to assume these will be fast-tracked for approval.

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Originally published on Forbes (May 11, 2021)

© William A. Haseltine, PhD. All Rights Reserved.