• Posted July 23, 2025

COVID Boosters Protect People With Cancer

Cancer patients can be very vulnerable to a severe COVID infection, but COVID-19 vaccine boosters can be lifesavers for them, a new study says.

COVID boosters reduced cancer patients’ hospitalizations and ICU stays by 29%, researchers report in JAMA Oncology.

Overall, the vaccine boosters prevented one hospitalization or ICU admission for every 150 to 166 boosted patients, researchers found.

“The reduction in hospitalizations was significant, and the number of patients we needed to treat to see a benefit to the boosters is quite low,” said senior researcher Jan Figueiredo, director of community health and population research at Cedars-Sinai Medical Center in Los Angeles.

“This shows a great benefit to our cancer patients and should encourage patients to discuss vaccination with their healthcare providers,” she said in a news release.

“Their immune systems can be weakened by their disease and the treatments they receive, which is why major health organizations recommend that these patients be vaccinated against COVID-19,” Figueiredo said.

For the new study, researchers analyzed data on more than 161,000 patients treated for cancer in 2022 and 2023 at Cedars-Sinai, Kaiser Permanente Northern California, Northwell Health in New York and the Veterans Health Administration.

Overall, the percentage of cancer patients who got COVID boosters was quite low, Figueiredo said. 

By January 2022, 68% had gotten a booster, and only 38% received subsequent boosters that targeted more than one COVID strain.

“Whether this is due to patient concerns about safety or provider uncertainty about whether to administer a vaccine during treatment is not clear,” Figueiredo said. “What is clear is that we need to advocate strongly for vulnerable groups, including cancer patients, to receive these vaccines.”

This is the largest study to date examining the effectiveness of COVID vaccines and boosters among cancer patients, she noted.

“It adds substantially to our understanding of the effectiveness of COVID-19 vaccines, and we will undertake additional studies as vaccine formulations change and new variants emerge so that we can make recommendations that best protect the health of our patients,” Figueiredo said.

Future research will examine vaccine effectiveness in other groups, such as people with autoimmune diseases and those who’ve had organ transplants, the team said.

“There are several different groups whose immune systems have been affected in different ways, which gives us an opportunity to expand further our understanding of how these vaccines work,” Figueiredo said.

More information

The American Cancer Society has more on cancer patients and COVID vaccines.

SOURCE: Cedars-Sinai Medical Center, news release, July 17, 2025