Two shots of a COVID-19 vaccine reduced the risk of hospitalization by 94 percent for people over 65, according to a new report from the Centers for Disease Control and Prevention.

That age group is at the highest risk of severe cases of COVID-19 — that’s why it was prioritized for the early waves of vaccination in the United States. Keeping that age group out of the hospital would go a long way to drive down the hospitalization rates from the disease overall.

The analysis looked at people hospitalized at 24 hospitals in 14 states during January, February, and March. It included 417 hospitalized patients, 187 of whom tested positive for COVID-19 and 230 who did not. Partial vaccination, defined in this case as having a first dose two weeks before starting to feel sick, was 64 percent effective against hospitalization. The shots were 94 percent effective for people who were fully vaccinated, two weeks out from their second dose.

Image: Centers for Disease Control and Prevention

The data is consistent with the clinical trials testing the Pfizer / BioNTech and Moderna vaccines, which found that the shots would keep people out of the hospital. But because only a small percentage of people with COVID-19 need to be hospitalized, the trials themselves didn’t have enough data to say how well they prevent hospitalization in the 65-plus age group, the CDC report notes. This real-world analysis adds more data to answer that question.

The study is yet another sign that the COVID-19 vaccines are overwhelmingly effective. Other data collected over the past few months found that the shots protect against infection with the coronavirus, not just symptomatic disease, and that they work well against variant forms of the virus.

Around 68 percent of people over 65 in the United States are fully vaccinated.