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%.
Misconception: Effectiveness
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,