Pfizer's booster dose is ineffective against Omicron after a short time
The protection offered by the Pfizer/BioNTech booster dose against the Omicron variant of the coronavirus diminishes after a few months, according to a study published Monday in The Lancet Respiratory Medicine.
"Pfizer/BioNtech's Covid-19 booster vaccines significantly improve protection against the Omicron variant, but three months after injection, effectiveness against hospital admissions declines," explains US epidemiologist Sara Y. Tartof of the Kaiser. Permanent Health Consortium, lead author of the study. However, high resistance to the virus remains, she notes.
The study, conducted between December 2021 and February 2022, looked at 11,123 hospital admissions and emergency room visits that did not result in hospitalization. At that time the Delta and Omicron variants were circulating.
The Pfizer-funded study shows that for the Omicron variant, efficacy against hospitalizations was 85% for those who received a third dose within three months, but fell to 55% for people who received it earlier.
A similar drop in efficacy is also seen against the Delta variant, although a third dose seems increasingly effective.