Paxlovid Is Far More Effective in Seniors Than in People Under 65, Study Finds

Taking the antiviral treatment Paxlovid can reduce a person’s chances of getting seriously ill from COVID-19. But while seniors tend to get impressive protection from the pills, younger people derive little benefit, finds new research.

In a study published Aug. 24 in the New England Journal of Medicine, researchers in Israel provide valuable real-world data on how effective the pills are against Omicron. The researchers studied data from 109,000 patients at a large health care organization—nearly all of whom had been vaccinated, had been previously infected, or both—and tracked their hospitalization and death rates by age. Nearly 4,000 people in the study, which was conducted from January to March 2022, took Paxlovid.

People who were 65 or older had a 73% lower chance of being hospitalized for COVID-19 and about a 79% lower chance of dying of the disease, compared to people in the same age group who did not take Paxlovid. But people ages 40 to 64 experienced no statistically significant drop in the risk of hospitalization or death.

Based on the findings, the authors conclude that “no evidence of benefit was found in younger adults.”

To qualify for Paxlovid, patients must be at elevated risk of developing serious illness from COVID-19. Risk factors include older age, as well as conditions such as obesity, high blood pressure, diabetes, and a history of heart and kidney failure. But the Israeli data suggest that age may be an even more important consideration for evaluating who should take it.

While the benefits are clear for seniors, the findings throw into question whether taking the drug is worth it for people under 65. It comes with potential side effects, including diarrhea, muscle aches, an increase in blood pressure, and an aftertaste so bad that it can temporarily affect some people’s ability to eat. Paxlovid also interacts with common medications, such as cholesterol-lowering statins, so some doctors advise patients to stop or reduce those medications during the five-day Paxlovid course. And there are increasing reports that people taking Paxlovid are likely to experience a rebound infection, or having the virus re-emerge after they stop taking the pills.

One caveat of the study is that the researchers did not break down data on younger people with cancer and other severe immunocompromising conditions, who may be more likely than other young people to benefit from Paxlovid—perhaps to a greater extent than the data showed. As more people take the medications, doctors will have a better understanding of who will benefit most, and for whom the benefits outweigh the risks.

Contact us at letters@time.com.