NBC News

Pfizer Says Vaccine’s Power Wanes Over Time. Are You Still Protected ?

The effectiveness of the Pfizer-BioNTech Covid vaccine waned over six months, but experts say the data still don't point to an immediate need for booster shots. The study, which hasn't yet been peer-reviewed or published in a medical journal, found that the vaccine was 97 percent effective at preventing severe disease from Covid-19 for at least six months .