Pfizer Studying Effects of 3rd Dose of COVID-19 Vaccine

A pharmacist prepares a syringe with the Pfizer-BioNTech COVID-19 vaccine at a COVID-19 vaccination site in New York City, on Feb. 18, 2021. AP Photo/Mary Altaffer

Pfizer and its partner are conducting a new trial that will evaluate the effects of a third dose of their COVID-19 vaccine, in a bid to protect against the virus variants circulating around the world.

Pfizer and BioNTech’s vaccine is currently given in two doses spaced several weeks apart.