Increasing Doses May Improve Efficacy of COVID-19 Vaccines in Cancer Patients

After 3 or 4 doses, mRNA-based COVID-19 vaccines are similarly effective in reducing the risk of severe COVID-19 or hospitalization for patients with cancer and the general population, according to research published in JAMA Oncology.

During the delta wave and 2022 omicron wave, cancer patients and control patients had lower rates of severe COVID-19 and COVID-19 hospitalization if they received 3 or 4 doses of an mRNA vaccine than if they received only 2 doses.

However, there was no significant difference in the incidence of COVID-19 by vaccine dose for cancer patients or control individuals.

For this study, researchers in Singapore examined the association between COVID-19 outcomes and vaccine doses over 2 time periods: September 15, 2021, to December 20, 2021 (delta wave), and January 20, 2022, to November 11, 2022 (omicron wave).

The analysis included 73,608 cancer patients — 23,217 with active cancer and 50,391 cancer survivors — and 621,475 matched control individuals. Vaccinated patients received Pfizer-BioNTech’s BNT162b2 vaccine or Moderna’s mRNA-1273 vaccine.

The researchers noted that, during both the delta and omicron waves, the incidence rate ratios (IRRs) for COVID-19 were not significantly different by vaccine dose for cancer patients or control individuals. There were no significant differences in the incidence of COVID-19 between patients who received 0-1 vaccine dose, those who received 2 doses, and those who received 3 or 4 doses.

On the other hand, the IRRs for COVID-19 hospitalization were significantly lower for cancer patients, cancer survivors, and control patients who received 3 or 4 doses of an mRNA vaccine than for those who received 2 doses.

Similarly, the IRRs for severe COVID-19 were significantly lower for cancer patients, cancer survivors, and control patients who received 3 or 4 doses of an mRNA vaccine than for those who received 2 doses.

The researchers noted that, during the delta wave, vaccine effectiveness against severe COVID-19 or hospitalization after 2 doses did not wane for cancer patients on active treatment or for cancer survivors. The researchers wrote that this was “remarkable given the significant waning demonstrated in the control group from 150 days postvaccination.”

During the omicron wave, there was no significant waning of vaccine effectiveness against severe COVID-19 or hospitalization after 3 doses for either the cancer or the control cohorts. However, vaccine effectiveness against SARS-CoV-2 infection did wane.

“The results of this cohort study provide evidence of the benefit of early vaccination and administration of booster vaccine doses against COVID-19 in patients with cancer, especially in conferring protective effects of vaccination against adverse outcomes of COVID-19,” the researchers wrote. “The findings also provided insight into the longevity of vaccine-mediated protection against clinical infection outcomes in both immunocompromised patients with cancer, with or without active treatment, and the general population.”

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Reference

Tan WC, Tan JYJ, Lim JSJ, et al. COVID-19 severity and waning immunity after up to 4 mRNA vaccine doses in 73 608 patients with cancer and 621 475 matched controls in Singapore: A nationwide cohort study. JAMA Oncol. Published online July 13, 2023. doi:10.1001/jamaoncol.2023.2271

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