Facebook Twitter Tumblr Close Skip to main content
A Project of The Annenberg Public Policy Center
SciCheck’s COVID-19/Vaccination Project

How effective are the vaccines?

All of the authorized and approved vaccines are effective at preventing symptomatic disease.
The Pfizer/BioNTech vaccine, which is the first COVID-19 vaccine to receive full approval from the Food and Drug Administration, showed a final efficacy of 91% against symptomatic illness in its phase 3 trial, meaning that under the conditions of the trial the vaccine reduced the risk of getting sick by 91%. The Moderna vaccine showed similar results in its clinical trial, with an efficacy of 94% against disease at the time of emergency use authorization.

How long will a person be protected if vaccinated?

Scientists don’t know how long protective effects of the vaccines will last, but clinical trials, which are continuing, are trying to determine the answer.
Dr. Peter Marks, the head of the FDA’s Center for Biologics Evaluation and Research, said in December that based on the experience of people who were immunized earliest in the trials, it appears that protection against the disease lasts at least several months.
By the summer of 2021, a few studies have shown a drop in vaccine effectiveness against infection,

A Guide to Moderna’s COVID-19 Vaccine

A Guide to Moderna’s COVID-19 Vaccine

Moderna’s mRNA vaccine is the second COVID-19 vaccine authorized for use in the U.S. Here, we give a rundown of basic facts about the vaccine and an overview of how it works.

Q&A on COVID-19 Vaccines

Q&A on COVID-19 Vaccines

Three COVID-19 vaccines are now authorized in the U.S. In this story, we answer some common questions about the shots.