COVID-19 vaccines are effective in most cancer patients, but less so than in the general population and the efficacy wanes more quickly, according to a large study.
When the Delta variant of the coronavirus was predominant in the UK, researchers tracked 377,194 individuals with cancer and more than 28 million people without malignancies.
After two doses of a COVID-19 vaccine from Pfizer /BioNTech  or AstraZeneca, overall vaccine effectiveness against infection was 69.8% in the general population and only slightly lower, at 65.5%, for cancer patients, the researchers reported on this week in The Lancet Oncology.
Three-to-six months later, however, vaccine effectiveness was 61.4% in the general population but had dropped to 47% in the cancer group. The vaccines were 83.3% effective against COVID-related hospitalization and 93.4% effective against death for cancer patients, but this protection also waned within three-to-six months, the researchers said.
Vaccine effectiveness was lowest and waned most quickly in people with lymphoma or leukemia. In cancer patients who had received chemotherapy or radiotherapy in the past 12 months, vaccine effectiveness was lower and waned faster than in cancer patients who did not receive treatments within the past year.
“This study… highlights the importance of vaccination booster programs and rapid access to COVID-19 treatments for people undergoing cancer treatments,” study leader Peter Johnson of the University of Southampton said in a statement.
