Pfizer-BioNTech Announces They Will Test a Third Dose of Their COVID-19 Vaccine

Pfizer-BioNTech has begun testing a third dose of its COVID-19 vaccine in a small group of people. The vaccine is currently authorized in several countries in a two-dose regimen, given 21 days apart, and has proven in studies to be about 95% effective in protecting against COVID-19 disease. But as new (and more infectious) genetic variants of the COVID-19 virus start circulating—so far, scientists have identified three major strains, first found in the U.K., South Africa, and Brazil, respectively—questions about how well authorized vaccines can still thwart the virus have become more urgent. Pfizer-BioNTech have already done studies testing blood serum from people vaccinated with their original shot against some of these variants, and found that the immune response triggered by the two doses is still quite protective. In fact, in the case of the U.K. variant (referred to as B.1.1.7), levels of antibodies produced by the vaccine regimen, an important immune defense against the virus, were similar to levels against the original, non-mutated virus. However, the researchers found that the level of antibodies produced by the original vaccine were lower against the South African variant (referred to as B.1.351). Pfizer-BioNTech hasn’t yet completed the same level of rigorous testing against the Brazilian variant (referred to as P1). “So far we haven’t heard any reports of breakthrough cases [among vaccinated people] related to any of the new variants,...
Source: TIME: Health - Category: Consumer Health News Authors: Tags: Uncategorized COVID-19 Source Type: news