PASADENA, Calif. — Research published in The Lancet Respiratory Medicine and then supplemented with additional analysis shows that a booster dose of the Pfizer COVID-19 vaccine provides strong protection, roughly 80% in the first few months against hospital admissions and emergency department visits caused by the delta and omicron variants. However, against omicron, this protection wanes over time for immunocompromised individuals — even after a third dose.
“Pfizer BioNTech COVID-19 booster doses significantly improve protection against omicron, although while that protection stays high for immunocompetent patients, it seems to wane for immunocompromised patients after 3 months against emergency room visits, and even for hospitalization,” said the study’s lead author, Sara Y. Tartof, PhD, an epidemiologist with the Kaiser Permanente Southern California Department of Research & Evaluation and a faculty member of the Kaiser Permanente Bernard J. Tyson School of Medicine, both in Pasadena.
For this study, the researchers analyzed 11,123 hospital admissions and emergency department visits that did not result in hospital admission for acute respiratory infection. The study focused on Kaiser Permanente patient records in Southern California from December 1, 2021, through March 18, 2022, when both the delta and omicron variants were circulating.
“Although the Pfizer COVID-19 protection levels against omicron after 3 doses are substantially higher than those seen after 2 doses, they are less than those observed for delta or other COVID-19 strains,” Tartof said. Further, immunocompromised persons appear at greatest risk of waning immunity, for whom “additional doses of current, adapted, or novel COVID-19 vaccines are needed to maintain high levels of protection against subsequent waves of COVID-19 caused by omicron or future variants with similar potential to escape protection.”
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