TUCSON, Ariz. (KGUN) — As the COVID-19 vaccine is being approved and tested for different groups of people, University of Arizona Cancer Center researchers found in a new study that those with cancer need three doses of vaccine for enough protection from the virus.
"The COVID-19 pandemic has dramatically impacted patients with cancer and other patients who are immunocompromised," Dr. Rachna Shroff, the director of the Cancer Center Clinical Trials Office at UA, said.
Shroff and a team of researchers compared the level of immunity in 53 cancer patients that were on active cancer therapy, such as chemotherapy treatments, to a group of 50 healthy patients. The immunity for cancer patients on treatment was measured after the first and second dose of the Pfizer vaccine.
Shroff said chemotherapy attacks both the cancer and the immune cells that defend the body from infection.
“We decided to look at a very clean cohort of patients with solid tumors, so primarily breast and gastrointestinal cancers on patients who are on active what we call cytotoxic therapy," Shroff said. "So whether that be things like chemotherapy or oral therapies that diminish your immune system."
After two doses of the vaccine, the level of immunity wasn't as strong as it was in healthy patients.
“We found that while patients with cancer on active therapy did develop some immunity to the COVID-19 vaccine, it seemed to be a diminished response," she said.
23 of the patients came back for a third dose of the vaccine, which boosted the immune response the most, showing similar levels to those not taking chemotherapy.
“We gave the some of those patients a third dose or a booster dose and that immunity improved," she said.
While the study shows levels of protection for cancer patients on chemotherapy, Shroff said it's still important to follow all safety precautions like masking and social distancing.
“I still tell my patients, even when they've had their booster that I think we need to take risk mitigation into account, and we need to wear masks when we're indoors," she said.
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