Pfizer COVID-19 vaccine 90% effective at preventing hospitalization, but weakens in preventing milder infections --study

Pfizer COVID-19 vaccine 90% effective at preventing hospitalization, even with delta variant: Study Pfizer's COVID-19 vaccine is still 90% effective at preventing hospitalization from the virus six months after it is administered, a new study found. ABC News ABC News

The Pfizer COVID-19 vaccine remains 90% effective at reducing a person's risk of hospitalization from the virus six months after it is administered, a new study has found. This is true even in the face of the delta variant as well as if the person has not received a booster shot.

Still, when it comes to preventing infections, the vaccine's effectiveness wanes rapidly as time passes, the study found. After five months, it is just 47% effective at preventing infection.

In the study, funded by Pfizer, researchers assessed data from Kaiser Permanente and calculated the percentages of fully vaccinated patients who contracted COVID-19 on a monthly basis after vaccination. Data from roughly 3.4 million people was analyzed between December 2020 and August 2021.