COVID-19 Boosters Help Keep People Out of the Hospital, Study Finds

As new Omicron-specific boosters become available in the U.S., a study published today in JAMA Internal Medicine emphasizes the importance and success of boosters in keeping people infected with COVID-19 out of the hospital.

The researchers analyzed data from more than 192,000 adults in 13 U.S. states who had been hospitalized with COVID-19 between January and April 2022 —when the original Omicron variant was at its peak. During this time, unvaccinated people were 10.5 times more likely to be hospitalized than people who had been fully vaccinated and boosted (with the original version of the booster). People who were vaccinated but not boosted were 2.5 times more likely to end up in the hospital than those who had received a booster.

This “underscores the importance” of boosters in preventing hospitalizations, serious illness, and death, the study authors write. The researchers call on clinicians and public-health practitioners to “continue to promote vaccination with all recommended doses for eligible persons.”

Only about 48% of eligible people in the U.S. have received a first booster shot, according to the latest data from the U.S. Centers for Disease Control and Prevention (CDC). And while 80% of people in the U.S. have received at least one dose of the vaccine, this isn’t enough to provide adequate protection against severe infection. Studies from researchers and COVID-19 vaccine makers suggest that the protection provided by the vaccines wanes over time. As the findings from one Moderna study suggest, vaccine-induced immunity is likely strongest soon after people get their recommended two doses of the vaccine, and starts to weaken after that.

Read More: You Can Still Get Long COVID If You’re Vaccinated and Boosted

In the new study, those who were hospitalized and fully vaccinated were predominantly people over 58 years old. They were also more likely to have at least three underlying medical conditions and to be residents in long-term care facilities—suggesting that people with weaker immune systems do not gain the same amount of protection against COVID-19 as healthy people from vaccines and past infections. They also are more vulnerable to severe infection. Getting a booster helped improve protection for all age groups, including this one.

The study “gives further support for adults ages 65 years and older to stay up to date with their COVID-19 vaccination,” says the study’s lead author and CDC medical officer Fiona Havers. Other measures are also important to help protect against hospitalization of older or other vulnerable individuals, “such as early access to antiviral medications if eligible, improving ventilation, getting tested, and wearing a mask,” she says.

The researchers also found that Black and Hispanic patients were less likely to be vaccinated than white patients. “Given the racial and ethnic disparities seen throughout the pandemic, the association between race and ethnicity and vaccination status among hospitalized cases should be monitored closely,” the researchers write.

On Sept. 1, the CDC authorized new Omicron-specific shots developed by Moderna (available to adults 18 years and older) and Pfizer-BioNTech (for people ages 12 and up). Though data in humans have not yet been published, public-health experts believe the new booster—which replaces the old one—will be an important way to confer continued protection. “If you are eligible,” said CDC director Dr. Rochelle Walensky in a recent statement, “there is no bad time to get your COVID-19 booster and I strongly encourage you to receive it.”