Pfizer researching effects of 3rd COVID-19 vaccine dose
Extended interview: Expert explains how COVID-19 vaccines work and side effects after shots
Dr. Williams Moss, an epidemiologist and executive director of the International Vaccine Access Center at Johns Hopkins, explains how mRNA vaccines by Pfizer and Moderna work and why side effects are more likely after the 2nd dose.
NEW YORK (AP) - Pfizer announced Thursday that it has begun studying a third dose of its COVID-19 vaccine, part of a strategy to guard against mutated versions of the coronavirus.
Health authorities say first-generation COVID-19 vaccines still protect against variants that are emerging in different parts of the world. But manufacturers are starting to prepare now in case a more vaccine-resistant mutation comes along.
Pfizer said it will offer a third dose to 144 volunteers, drawing from people who participated in the vaccine’s early-stage U.S. testing last year. It wants to determine if an additional booster shot given six to 12 months after the first two doses would rev up the immune system enough to ward off a mutated virus.
Illustration picture shows the headquarters of pharmaceutical company Pfizer in Elsene - Ixelles, Brussels, Thursday 11 Feb. 2021. (Photo by NICOLAS MAETERLINCK/BELGA MAG/AFP via Getty Images)
Pfizer and its German partner, BioNTech, also are tweaking their vaccine recipe. The companies are in discussions with U.S. and European regulators about a study to evaluate doses updated to better match variants such as the one first discovered in South Africa.