The Pfizer vaccine offers between 80% and 90% protection against Covid-19. But according to a new American study, this vaccination coverage would decrease after three months in the case of the Omicron variant.
- New US study finds Pfizer’s Covid-19 vaccine offers strong protection against hospital admissions and emergency room visits
- However, this protection is reduced after three months for cases of the Omicron variant
Posted in The Lancet Respiratory Medicine, the study was based on an analysis of 11,123 hospital admissions and emergency room visits that did not result in a hospital admission for an acute respiratory infection. The study focused on the files of patients admitted to Kaiser Permanente (Southern California, United States) between December 1, 2021 and February 6, 2022, a period when the two Delta and Omicron variants were circulating in the territory studied.
The authors of the work found that after two doses of the Pfizer Covid-19 vaccine, efficacy against Omicron was 41% against hospital admission and 31% against emergency room visits at 9 months. After three doses, the vaccine’s effectiveness rate against them dropped from 85% to 55% after three months. Against emergency room visits that did not result in hospitalization, the efficacy of the omicron vaccine after three doses was 77%, but fell to 53% three months later.
“Booster doses of Pfizer BioNTech COVID-19 significantly improve protection against Omicron, although this protection appears to fade after three months against ER visits and even hospitalizationsnotes Sara Y. Tartof, an epidemiologist in the Research and Evaluation Department at Kaiser Permanente Southern California, who led the study.
“Attenuation-related outcome trends relative to the Delta variant were generally similar to those of Omicron, but with higher efficacy at each time point than those observed for the Omicron variant“, she adds.
