FOR PROTECTION AGAINST COVID-19 this fall and winter, the Centers for Disease Control and Prevention (CDC) recommends that everyone age 5 and older get one dose of an updated Pfizer-BioNtech, Moderna or Novavax COVID-19 vaccine. If you got previous COVID-19 vaccines before Sept. 12, 2023, the CDC recommends getting one updated COVID-19 vaccine now to guard against serious illness.

Those who are moderately or severely immunocompromised, such as those undergoing cancer treatment, may get additional doses of the updated COVID-19 vaccine, according to the CDC. So, how often should you get a COVID-19 booster if you fall into that category?

“Because the CDC guidance is vague, doctors don’t have a specific plan for what they should do, but the flexibility also allows them to do as they find most suitable for a given patient,” says Jeffrey Townsend, co-leader of the Genetics, Genomics and Epigenetics Research Program at Yale Cancer Center in New Haven, Connecticut. A study in the Aug. 21 issue of the Journal of the National Cancer Institute that Townsend and his research team conducted provides guidance for patients undergoing treatment with Rituxan (rituximab), which is used to treat certain types of cancer, such as non-Hodgkin lymphoma and chronic lymphocytic leukemia.

“What determines whether you are likely to get an infection or not is the level of antibodies you have, which declines over time,” Townsend says. “Rituximab substantially decreases the amount of antibodies you get as a response to a vaccination.” Fewer antibodies on board makes it more likely that you will become infected with COVID-19 or another illness. “If you get boosted more frequently, it boosts up those antibodies,” Townsend says, and your body’s ability to fight COVID-19.

Help Yourself Stay Healthy This Season

Vaccines along with other healthy practices can protect you from COVID-19 and other seasonal illnesses.

In fact, the study found that patients who are severely immunocompromised due to rituximab therapy may benefit from a COVID-19 booster as often as every three months. Specifically, patients undergoing rituximab therapy who don’t receive any COVID-19 boosters have a 45% chance of being infected with COVID-19 over two years. With a COVID-19 booster every year or every six months, the chances of getting COVID-19 drop to 36% and 27%, respectively. With a booster every three months, the risk of contracting COVID-19 in these immunosuppressed patients is just 22%. “That may not sound like a huge decrease, but if you are immunosuppressed, especially with rituximab, the severity of a COVID-19 infection can be severe,” Townsend says.

The increased COVID-19 vaccination schedule may also apply to other types of cancer therapy that severely suppress the immune system. “There’s not much reason to hesitate about a COVID-19 booster more frequently for those individuals who are at a special risk of severe infection,” Townsend says. 

Immunocompromised people should talk to their doctor about a seasonal vaccine schedule that’s right for them, Townsend says, which may vary based on where they are undergoing cancer treatment. At University of Texas MD Anderson Cancer Center in Houston, for example, the recommendation is that patients receive all seasonal vaccines, but with some nuances. “For patients undergoing a heavily immunosuppressive treatment, such as conditioning regime for stem cell transplants or CAR T-cell therapy or taking high-dose steroids, it’s best to get vaccinated before they get started or after they recover from therapy because otherwise, they may not respond to the vaccine,” says Roy F. Chemaly, director of clinical virology research at MD Anderson.

Patients receiving cancer treatment at MD Anderson who are not severely immunocompromised are advised to get the new COVID-19 shot and other seasonal vaccines. “Prevention from seasonal viruses for people with cancer is important because the outcome from contracting the infection could be severe,” Chemaly says. “Even if you are in remission, you may have other issues or complications from cancer treatment that can increase the risk for severe outcomes.” Chemaly adds that even patients with cancer who may only be able to mount a partial immune response to seasonal viruses may be protected against severe infection, hospitalization or even death.

Sandra Gordon is a medical writer in Stamford, Connecticut.