COVID-19 booster shots confer protection against severe disease in cancer patients

Patients with cancer who have received COVID-19 booster vaccinations are better protected against severe disease, according to real-world data from four healthcare systems in the US.

In a cohort of 72,831 participants with cancer (24.6 percent female), the rate of COVID-19 hospitalization was 30.5 per 1,000 person-years among patients who received an additional dose of the monovalent vaccine vs 41.9 per 1,000 person-years among those who completed the primary vaccine series only. The corresponding vaccine effectiveness was 29.2 percent, while the number needed to vaccinate (NNV) to prevent one COVID-19 hospitalization was 166. [JAMA Oncol 2025;doi:10.1001/jamaoncol.2025.2020]

The receipt of a monovalent booster dose was also associated with reduced rates of diagnosed COVID-19 (216.3 vs 241.8 per 1,000 person-years) and COVID-19–related ICU admission (9.2 vs 13.3 per 1,000 person-years), with a vaccine efficacy of 8.5 percent and 35.6 percent, respectively. The corresponding NNV was 110 to prevent one episode of diagnosed COVID-19 and 423 to prevent one COVID-19–related ICU admission.

Findings were similar among patients with solid malignant neoplasms and those with hematologic malignant neoplasms.

Bivalent vaccine

During the bivalent vaccine period, the COVID-19 hospitalization rate was lower among cancer patients who did vs did not receive a bivalent vaccine (13.4 vs 21.7 per 1,000 person-years), with a vaccine efficacy of 29.9 percent and an NNV of 451 to prevent one COVID-19 hospitalization.

COVID-19–related ICU admissions were also lower among those who received a bivalent vaccine (3.3 vs 5.4 per 1,000 person-years), with a vaccine efficacy of 30.1 percent and an NNV of 1,805 to prevent one ICU admission. However, receipt of a bivalent vaccine did not lead to a substantially reduced COVID-19 diagnosis (112.0 vs 116.8 per 1,000 person-years), with a vaccine efficacy of only 2.9 percent.

The analysis included 72,831 patients with cancer (24.6 percent) with 34,006 person-years of follow-up during the monovalent COVID-19 vaccine booster period (1 January 2022 to 31 August 2022) and 88,417 patients with cancer (27.8 percent female) with 81,027 person-years of follow-up during the bivalent COVID-19 vaccine period (1 September 2022 to 31 August 2023).

Low uptake

“This is the largest epidemiologic study of COVID-19 booster vaccine efficacy in patients with cancer, a high-risk population of critical importance and uncertain immunologic function,” the investigators said.

They pointed out that COVID-19 vaccine uptake among this population was notably low, even with widespread availability. Just 69 percent of the patients received the monovalent booster, and even fewer—only 38 percent—received a bivalent vaccine.

“Given the vaccine efficacy against severe COVID-19 illness and the favourable NNV reported herein, interventions to improve vaccine uptake in this high-risk population are urgently needed,” they said.

Implementing structured vaccination protocols in oncology clinics has proven successful in increasing vaccine uptake among cancer patients, they continued. Key components of these protocols include electronic reminders to identify eligible patients, standing orders, and nurses administering vaccines during routine cancer care encounters. [J Clin Oncol 2024;42:1699-1721]

The investigators highlighted the ongoing need for research. Future efforts should focus on understanding the long-term duration of vaccine protection in cancer patients, developing more effective vaccine technologies, determining the optimal timing of vaccination around cancer treatments, and establishing the mechanisms underlying attenuated immune responses in this vulnerable population, they said.