Fast Five Quiz: COVID-19 Vaccines

Glenn Wortmann, MD


August 02, 2022

Patients with cancer appear to be more likely than those without cancer to develop a less proficient immune response after vaccination against COVID-19. A real-world study by Embi and colleagues that included more than 89,000 people, of whom more than 10,000 had cancer, noted that prior to the prevalence of the Omicron variant, the vaccine efficacy of mRNA vaccines against COVID-19 hospitalization in patients with cancer was estimated to be approximately 75%, which is lower than the 90% in immunocompetent individuals. Advancing age further reduced vaccine efficacy. Nevertheless, experts from various cancer societies recommend vaccination for patients with cancer or for cancer survivors due to the high risk for COVID-19 in these populations.

Recent chemotherapy (defined inconsistently as receiving chemotherapy from within 28 days to within 6 months of vaccination) has been repeatedly identified as a risk factor for lower seroconversion and neutralizing responses. A review by Fendler and colleagues noted that the timing of the vaccination with regard to the schedule of ongoing chemotherapy does not seem to affect seroconversion, which is consistent with previous experience with double-dose influenza vaccination.

Patients who are either immunocompromised or immunosuppressed, such as those with cancer, may require more vaccine doses than those who are immunocompetent. In addition, vaccination strategies involving several doses have the added advantage of being effective irrespective of the timing of chemotherapy.

Studies have shown that patients with hematologic cancers have a higher risk of developing reduced immune responses to COVID-19 vaccination and a lower vaccine efficacy compared with non-immunocompromised individuals (74% vs 90%, respectively). Encouragingly, long-term survivors of hematologic cancers, including stem cell transplant recipients, have a response to vaccination similar to the general population, even if earlier therapy was very immunosuppressive.

Learn more about COVID-19 vaccines.

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