A new study by Israeli researchers found that cancer patients need two shots to achieve full immunity against COVID-19. The study published in JAMA Oncology focused on the Pfizer vaccine, which was the first to be approved in Israel.
According to the Daily Mail, researchers found that of the 232 cancer patients vaccinated with the Pfizer shot, only 29% developed antibodies to the virus, compared to 84% of the control group ― healthcare workers who did not have cancer. However, after the second dose of the vaccine, 86% of the cancer patients tested positive for antibodies.
Cancer patients are at increased risk for COVID-19 but were not included in the clinical trials for the vaccines. The new study illustrates the efficacy of the vaccines in this population. Some scientists are suggesting that cancer patients receive a third shot, a booster dose to protect them even further from severe illness.
The Centers for Disease Control and Prevention warns that treatments for many types of cancer can weaken the body’s ability to fight off COVID-19. Specific cancers, including lung, blood, and bone marrow cancers, are considered to place patients at an extremely high risk from COVID infection.
Healthcare officials therefore consider cancer patients to be a priority population for vaccination. And scientists were worried that the same compromised immune system that made this group more vulnerable to COVID-19 might make the vaccines less effective, says the Daily Mail.
The new study backs up research from Montefiore Health System and Albert Einstein College of Medicine in Bronx, N.Y. last month that found that 94% of patients with cancerous tumors received immunity after full vaccination from either the Pfizer or the Moderna shots. Some of the study participants received the Johnson & Johnson one-dose vaccine. The study subjects who had the Pfizer or Moderna vaccines were more likely to test positive for antibodies, according to news reports.
Last March, researchers in the U.K. found that a single dose of the Pfizer vaccine did not offer as much protection in cancer patients, particularly in patients suffering from blood cancer, as it does in healthy individuals.
According to CNN, the U.K. researchers studied 205 adults that included 54 healthy volunteers and 151 older patients with either solid cancers, such as breast or prostate cancer, or blood cancers, such as leukemia.
They measured antibody and T- cell levels in the participants after one dose of the Pfizer vaccine to evaluate the degree of protection generated by the shot.
After three weeks, the antibody response in the healthy volunteers was 97%, but in the patients with solid cancers, the reaction was only 39%. Patients with blood cancers had only a 13% response.
However, the solid cancer patients received a booster shot three weeks after the initial jab and their antibody response rose to 95%. According to CNN, there was not enough vaccine available at the time to give the blood cancer patients a second shot.
“Our data provides the first real-world evidence of immune efficacy following one dose of the Pfizer vaccine in immunocompromised patient populations,” said head researcher Dr. Sheeba Irshad, a clinical oncologist from the School of Cancer & Pharmaceutical Sciences at King’s College London. “We show that following first dose, most solid and hematological cancer patients remained immunologically unprotected up to at least five weeks following primary injection.”
Dr. Sheeba predicted that a second shot would boost immune response. The new Israeli study bears this out, and further notes that certain types of cancer and cancer treatment affect COVID-19 immunity.
In France, healthcare providers are giving a third dose of the vaccine to organ transplant recipient patients and those with weakened immune systems.
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