Pfizer Vaccine Successful Against Brazilian Variant, Laboratory Study Finds

The Pfizer/BioNTech COVID-19 vaccine demonstrated effectiveness against a Brazilian coronavirus strain that has quickly spread throughout the country, a study has found.

The study, published in the New England Journal of Medicine (NEJM) this week and conducted by the drugmakers and researchers at the University of Texas Medical Branch, pitted the vaccine against engineered versions of the Brazilian, UK and South African variants — mutations that have raised global fears that they may reduce vaccine protection and hinder vaccination efforts around the world.

The researchers, using 20 serum samples taken from 15 participants in the two companies’ phase 3 trial, found that the two-dose vaccine provided “roughly equivalent” neutralization against the Brazilian and UK strains compared to the normal SARS-CoV-2 virus. Against the South African variant, neutralization was “robust but lower,” they found, suggesting the vaccine may still work well against the worrisome mutation despite the apparent efficacy reduction.

Peter English, a consultant in communicable disease control for Public Health England — an agency of the Department of Health and Social Care — found the results reassuring, though he noted that the study was conducted in a laboratory setting, meaning it doesn’t paint a picture of how the Pfizer/BioNTech may fare against variants in real-life settings.

“These findings indicate that this vaccine is likely to be effective against the variants studied, although precisely how effective they are in the real world will require data on the vaccine’s actual effect in populations, not just in laboratory studies such as this one,” he said.

“This study adds to what we know about the efficacy of the immune response induced by the Pfizer/BioNTech vaccine. It does not claim that the vaccine will be effective against variant strains in the real world, but it is suggestive that it might be effective.”

Vaccine makers have begun prepping in case they need to make modifications to their COVID-19 vaccines to adapt them to viral variants, a topic the FDA has issued guidance on. The agency has said that it doesn’t expect to require data from large-scale trials to amend Emergency Use Authorizations (EUAs) for altered vaccines, with trials of a few hundred participants likely to suffice (DID, Feb. 23). The European Medicines Agency has also published guidance laying out its expectations for modified vaccines (DID, Feb. 26).

Read the NEJM study report here: bit.ly/3eiukDU. — James Miessler