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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 severe COVID-19.
Against earlier forms of the coronavirus, the vaccines were highly effective at preventing symptomatic illness. For example, the Pfizer/BioNTech vaccine, which was 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%.

How long will a person be protected if vaccinated?

It’s not known exactly how long vaccination lasts, particularly against the omicron variant. But studies of previous variants have suggested that COVID-19 vaccination protects against infection or mild disease for several months, while protection against more serious illness is longer-lasting, on the order of six months or more.
A systematic review of studies conducted prior to omicron, for example, found that for the four main COVID-19 vaccines used worldwide,

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 to be authorized and fully approved 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.