Pfizer and Moderna focus on COVID-19 variant booster shots

Moderna and Pfizer are both testing COVID-19 booster shots intended to address coronavirus variants of concern, the companies announced in separate press releases this week. Such third shots aren't yet available and, at this point in time, aren't needed; however, the presence of certain SARS-CoV-2 variants have the companies preparing as the pandemic evolves.

For its part, Pfizer announced on Thursday that it and BioNTech have kicked off a clinical evaluation about potentially using a third dose of their COVID-19 vaccine as a booster against SARS-CoV-2, including new possible variants. The evaluation aims to learn about the effects a third shot will have on one's immunity against the virus.

The study will focus on people in the United States who were part of Pfizer's Phase 1 evaluation, with the intention being a third 30mcg booster shot given between 6 and 12 months after getting the initial two-dose vaccination regime. Similarly, Moderna is evaluating booster candidates, as well a third dose of its COVID-19 vaccine, to study their effect on immunity against the virus and its variants.

As part of a Phase 1 clinical trial, Moderna says it has shipped mRNA-1273.351 variant-specific vaccine candidate to the National Institutes of Health to evaluate its potential against the South Africa SARS-CoV-2 variant called B.1.351. For its part, Pfizer says it and BioNTech are in talks with US and European authorities on a new clinical study intended to evaluate its own variant-specific vaccine targeting the same strain.

In a statement, Pfizer CEO Albert Bourla said:

While we have not seen any evidence that the circulating variants result in a loss of protection provided by our vaccine, we are taking multiple steps to act decisively and be ready in case a strain becomes resistant to the protection afforded by the vaccine. This booster study is critical to understanding the safety of a third dose and immunity against circulating strains. At the same time, we are making the right investments and engaging in the appropriate conversations with regulators to help position us to potentially develop and seek authorization for an updated mRNA vaccine or booster if needed.

The announcements come amid growing concerns over SARS-CoV-2 variants, particularly the strain first identified in South Africa. Evidence suggests the two vaccines currently available may be less effective against the variant. Public health officials are encouraging the public to get vaccinated as soon as possible, the goal being to reach a minimum threshold level for curbing the pandemic and preventing new variants from emerging.