Vaccine maker Pfizer said Friday that trials of its vaccine in children ages 2 to 5 show that it did not provide the expected immunity in kids this age, and it is adding a third dose to the regimen.

A third dose of the Pfizer/BioNTech COVID-19 vaccine can "strongly" boost protection against the delta variant -- beyond the protection afforded by the standard two doses, suggests new data released ...

LOS ANGELES -- The COVID-19 vaccines made by Pfizer and Moderna both require two doses to be administered, several weeks apart, for them to be fully effective. But there has been some scientific ...

Britain on Wednesday became the first country in the world to approve the Pfizer-BioNTech , COVID-19 vaccine for use and said ...

On December 18, a San Diego emergency room nurse was given a shot of the COVID-19 vaccine. A week later, he tested positive for the virus, CNN affiliate KGTV reported. Stories like this will become ...

Nearly 2 million COVID-19 vaccine doses have been administered in the US, according to the Centers for Disease Control and Prevention, and more than 9.5 million doses have been distributed. While ...