September 23, 2022

Study indicates COVID-19 boosters among vaccinated individuals significantly reduce hospitalization rates

Odds of hospitalization for Covid-19 after 3 vs 2 doses of mRNA Covid-19 vaccine by time since booster dose. The shaded areas indicate the 95% CIs. The 30-day rolling average is depicted. Credit: JAMA (2022). DOI: 10.1001/jama.2022.17811

A Providence study released online today in the Journal of the American Medical Association sheds new light on the added benefit of a booster dose of a COVID-19 mRNA vaccine among previously vaccinated individuals.

Researchers found that boosters add about 70% extra protection, which lasts for 4–5 months, and concluded that booster vaccination is associated with significantly decreased odds of hospitalization for COVID-19 among fully vaccinated individuals. Odds of decreased hospitalization varied based on time since booster administration.

While previous studies have established the association between boosters and decreased risk of developing severe COVID-19 when compared with unvaccinated individuals, this study is unique in its focus on individuals who are already fully vaccinated with the primary series of an mRNA vaccine. It adds to the growing body of research around the effect of booster doses in various populations.

This research shows us that even if you're fully vaccinated, there's a real value to getting a booster," said Ari Robicsek, M.D., Providence's chief medical analytics officer and senior author of the study. "Compared to people who only had their initial vaccinations, people with boosters were a lot less likely to have severe COVID for 4–5 months after the shot."

Providence, a not-for-profit health system serving the Western U.S., conducted the research at sites across six western states. It matched 3,052 cases hospitalized for COVID-19 within a Providence facility 4:1 with 12,248 controls admitted to a Providence facility non-electively for reasons other COVID-19. Cases were hospitalized between October 1, 2021, and July 26, 2022, and controls were admitted to a facility within three days in the same as their case and received a second vaccine within seven days of their case.

More information: Odds of Hospitalization for COVID-19 After 3 vs 2 Doses of mRNA COVID-19 Vaccine by Time Since Booster Dose, JAMA (2022). DOI: 10.1001/jama.2022.17811

Journal information: Journal of the American Medical Association

Provided by Providence Health & Services

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