The study, which was published in the New England Journal of Medicine on Tuesday, found that effectiveness against infection in the fourth week after the second booster shot was lower than protection mounted after the third vaccine dose. The protection drastically falls after eight weeks.
Researchers concluded that “these findings suggest that protection against confirmed infection wanes quickly.”
Cartoons on the Coronavirus
Protection against severe illness, however, didn’t wane during the six weeks after the fourth shot, according to the study. But researchers reported that “more follow-up is needed in order to evaluate the protection of the fourth dose against severe illness over longer periods.”
The study focused on adults ages 60 and older and examined 1.25 million vaccinated people in Israel from Jan. 10 to March 2, when the omicron variant was the dominant strain.
The research comes just about a week after the Food and Drug Administration authorized an additional coronavirus booster shot for Americans ages 50 and older at least four months after their third dose, citing waning protection from previous shots.
The agency cited data out of Israel showing “increases in neutralizing antibody levels against SARS-CoV-2 virus, including delta and omicron variants were reported two weeks after the second booster as compared to 5 months after the first booster dose” for its decision, which came without a meeting or endorsement from its vaccine advisory committee.
Leading infectious disease expert Anthony Fauci said during a press briefing on Tuesday that “booster shots protect against serious illness, hospitalizations and even death” – notably not mentioning infection.