COVID-19 Vaccines and Cancer Patients: 4 Things to Know

Gabriel Miller

December 18, 2020

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Earlier this week, Medscape spoke with Nora Disis, MD, about vaccinating cancer patients. Disis is a medical oncologist and director of both the Institute of Translational Health Sciences and the Cancer Vaccine Institute, the University of Washington, Seattle, Washington. As editor-in-chief of JAMA Oncology, she has watched COVID-19 developments in the oncology community over the past year.

Here are a few themes that Disis said oncologists should be aware of as vaccines eventually begin reaching cancer patients.

We should expect cancer patients to respond to vaccines. Historically, some believed that cancer patients would be unable to mount an immune response to vaccines. Data on other viral vaccines have shown otherwise. For example, there has been a long history of studies of flu vaccination in cancer patients, and in general, those vaccines confer protection. Likewise for pneumococcal vaccine, which, generally speaking, cancer patients should receive.

Special cases may include hematologic malignancies in which the immune system has been destroyed and profound immunosuppression occurs. Data on immunization during this immunosuppressed period are scarce, but what data are available suggest that once cancer patients are through this immunosuppressed period, they can be vaccinated successfully.

The type of vaccine will probably be important for cancer patients. Currently, there are 61 coronavirus vaccines in human clinical trials, and 17 have reached the final stages of testing. At least 85 preclinical vaccines are under active investigation in animals.

Both the Pfizer-BioNTech and Moderna COVID vaccines are mRNA type. There are many other types, including protein-based vaccines, viral vector vaccines based on adenoviruses, and inactivated or attenuated coronavirus vaccines.

The latter vaccines, particularly attenuated live virus vaccines, may not be a good choice for cancer patients. Especially in those with rapidly progressing disease or on chemotherapy, attenuated live viruses may cause a low-grade infection.

Incidentally, the technology used in the genetic, or mRNA, vaccines developed by both Pfizer-BioNTech and Moderna was initially developed for fighting cancer, and studies have shown that patients can generate immune responses to cancer-associated proteins with this type of vaccine.

These genetic vaccines could turn out to be the most effective for cancer patients, especially those with solid tumors.

Our understanding is very limited right now. Neither the Pfizer-BioNTech nor the Moderna early data discuss cancer patients. Two of the most important questions for cancer patients are dosing and booster scheduling. Potential defects in lymphocyte function among cancer patients may require unique initial dosing and booster schedules. In terms of timing, it is unclear how active therapy might affect a patient's immune response to vaccination and whether vaccines should be timed with therapy cycles.

Vaccine access may depend on whether cancer patients are viewed as a vulnerable population. Those at higher risk for severe COVID-19 clearly have a greater need for vaccination. While there are data suggesting that cancer patients are at higher risk, they are a bit murky, in part because cancer patients are a heterogeneous group. For example, there are data suggesting that lung and blood cancer patients fare worse. There is also a suggestion that, like in the general population, COVID risk in cancer patients remains driven by comorbidities.

It is likely, then, that personalized risk factors such as type of cancer therapy, site of disease, and comorbidities will shape individual choices about vaccination among cancer patients.

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