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Protection with the third dose of COVID-19 vaccine against hospitalization decreases after 3 months

A new research study published in The Lancet Respiratory Medicine shows that protection against the omicron variant worsens over time – even after the third dose of the vaccine.

Kaiser Permanente found that the third dose of Pfizer COVID-19 protected against omicron hospitalization after 3 months.

A research study published on April 22, 2022 in The Lancet Respiratory Medicine shows that a booster dose of Pfizer COVID-19 provides strong protection, about 80% to 90%, against hospital admissions and emergency room visits in the first few months. caused by delta and omicron variants of COVID-19. However, this protection against omicron worsens over time – even after the third dose of the vaccine.

“Pfizer BioNtech COVID-19 boosts significantly improve protection against omicron, although this protection appears to weaken after 3 months of emergency room visits and even hospitalization,” said Sara Y. Tartof, PhD, epidemiologist Kaiser Permanente. Southern California Department of Research & Evaluation and a member of the Faculty of Medicine Kaiser Permanente Bernard J. Tyson, both in Pasadena. “The declining trends against delta-related outcomes were generally similar to omicron, but with higher efficiencies at each time point than omicron.”

The researchers examined 11,123 hospital admissions and emergency room visits that did not result in hospitalization for an acute respiratory infection. The researchers looked at records from Kaiser Permanente patients in Southern California from December 1, 2021 to February 6, 2022, when both delta and omicron variants circulated in the population.

  • After 2 doses of Pfizer COVID-19, the effectiveness against omicron was 41% against hospital admission and 31% against emergency department visits after 9 months.
  • After 3 doses, the omicron-related anti-hospitalization efficacy was 85% in less than 3 months, but decreased to 55% in 3 months or more.
  • Against non-hospital emergency visits, the effectiveness of the 3-dose omicron vaccine was 77% in less than 3 months, but dropped to 53% in 3 months or more.

“Although the levels of protection of Pfizer COVID-19 against omicron after 3 doses are significantly higher than those observed after 2 doses, they are lower than the levels observed with delta or other COVID-19 strains,” Tartof said. “Additional doses of current, adapted or new COVID-19 vaccines may be required to maintain a high level of protection against subsequent COVID-19 waves caused by omicron or future variants with a similar potential to escape protection.”

Reference: “Durability of BNT162b2 against hospital and emergency department admissions due to omicron and delta variants in the major US health care system: test-negative case-control study” by Sara Y Tartof, PhD; Jeff M Slezak, MS; Laura Puzniak, PhD; Vennis Hong, MPH; Fagen Xie, PhD; Bradley K Ackerson, MD; Srinivas R Valluri, PhD; Luis Jodar, PhD and John M McLaughlin, PhD, April 22, 2022, The Lancet Respiratory Medicine.DOI: 10.1016 / S2213-2600 (22) 00101-1