RSV Vaccine Succeeds in Phase III Trial of Older Adults End-shutdown

very important new study came out last week New England Journal of Medicine (NEJM), which found that an RSV vaccine candidate was highly effective in preventing lower respiratory tract (read: lung) disease. The study also found that the vaccine prevented severe disease.

The study has many of the characteristics you want to see in a well-conducted study: The vaccine was compared with a placebo, and the study was blinded, meaning that the participants and the scientists conducting the analysis did not know who received what. The study had nearly 25,000 participants and was conducted in 17 countries.

The vaccine was found to be over 80% effective against lower respiratory disease (the main outcome of the study was designed to measure) and 94% effective against severe disease. This is great news.

The study was conducted between May 2021 and January 2022, meaning that COVID-19 mitigation was still in place. As a result, the RSV rates were lower than we would normally expect, ie the rates were low in the placebo group and very low in the vaccinated group.

I was curious what this data might mean at the population level during a “normal year”. Assuming that the vaccine is also 94% effective in preventing RSV-related hospitalizations, I applied CDC surveillance data to the study findings to get a sense of the impact this vaccine could have for older people.

In the US, there are about 76.5 million people age 60 and older. In the last pre-COVID season, approximately 45.1 people in 100,000 in the entire US population 60 years and older had an RSV-related hospitalization. That means about 34,500 people in this age group were hospitalized in one season (2019-2020) with RSV. If the vaccine prevented 94% of these, that number would drop to just over 2,000. I think that’s a significant decrease, and the actual improvement may be even greater, as we get better at tracking RSV overall.

Other studythat is, out in NEJM, also encouraging the data found for a different vaccine platform. Along with these two research articles, a commentary describing the technical challenges ultimately overcome in RSV vaccine development was also published.

If we can decimate the flu, COVID, other RSV-related hospitalizations in the future, both patients and the healthcare system may finally get a well-deserved rest.

These new data are important pieces of that puzzle, and as the children say, “We love to see it!”

Jeremy Faust, MD, is editor-in-chief of Med Page today, and an emergency medicine physician at Brigham and Women’s Hospital. This post originally appeared on Internal Medicine.

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