But Uptake Remains Low
Click to Enlarge: Effectiveness of Bivalent COVID-19 Vaccine Compared With No Bivalent Vaccine to Prevent COVID-19 Hospitalization in Persons With Cancer and Nonimmunocompromised Persons, September 1, 2022-August 31, 2023aAbbreviations: HR, hazard ratio; NB, no benefit.
a. Pooled results from 4 health care systems.
b. See eTables 4 and 5 in Supplement 1 for definitions. Patients may have had more than 1 diagnosis and/or received more than 1 type of medication and were included in the analysis of each stratum in which they qualified.
c. Each site ran a Cox proportional hazards model on their own data, with bivalent vaccination as a time-dependent variable and adjusting for age, sex, race and ethnicity, Charlson Comorbidity Index score, and vaccination status as of the index date (September 1, 2022). Pooled HRs were calculated from the inverse variance–weighted fixed effects of the proportional hazards model results from each site.
d. Other gastrointestinal cancers included esophageal, pancreatic, gall bladder, anus, anal canal, and anorectum. Source: JAMA Network Open
PLEASANTON, CA — Additional doses of COVID-19 vaccines were significantly effective at preventing COVID-19 hospitalizations for cancer patients, according to a new study that involved four healthcare systems, including the VHA.
In the retrospective cohort study conducted from January 2022 to August 2023 among cancer patients in the United States, additional monovalent COVID-19 vaccines reduced COVID-19 hospitalizations by 29%, with a number needed to vaccinate of 166 in January to August 2022, and a bivalent COVID-19 vaccine reduced COVID-19 hospitalizations by 30%, with a number needed to vaccinate of 451 in September 2022 to August 2023, according to researchers from Kaiser Permanente Northern California and colleagues. The Louis Stokes Cleveland VAMC participated in the study.
“In both time periods, COVID-19 vaccination was associated with protection from severe COVID-19 among persons with cancer,” the researchers wrote in JAMA Oncology.1
The information is significant because cancer patients are at increased risk of severe COVID-19 infection, but the additional benefit of COVID-19 boosters had been unclear.
The study team sought to assess COVID-19 vaccine effectiveness (VE) and number needed to vaccinate (NNV) among cancer patients who received an additional dose of the monovalent COVID-19 vaccine.
The retrospective cohort study conducted in four healthcare systems in the United States among cancer patients receiving chemotherapy or immunotherapy. In addition to the VHA, the systems were Cedars-Sinai Health System, Kaiser Permanente Northern California [KPNC] and Northwell Health.
Statistical analysis was conducted between March 2023 and August 2024.
The focus was on the receipt of an additional dose of the monovalent COVID-19 vaccine before January 1, 2022, with follow-up until August 31, 2022, and the bivalent COVID-19 vaccine from September 1, 2022, to August 31, 2023.
The outcomes of interest were COVID-19 hospitalization, diagnosed COVID-19, and COVID-19–related intensive care unit (ICU) admission.
Among 72 ,831 cancer patients, more than 75% male, 69% received a monovalent booster by Jan. 1, 2022. During 34, 006 person-years of follow-up, the study found that the COVID-19 hospitalization rate was 30.5 per 1000 person-years among patients who received a monovalent booster vs 41.9 per 1000 person-years among patients who received the primary series alone, with an adjusted VE of 29.2% (95% CI, 19.9%-37.3%). The NNV to prevent 1 COVID-19 hospitalization was 166 (95% CI, 130-244).
“There was also significant VE to prevent diagnosed COVID-19 (8.5% [95% CI, 3.7%-13.0%]) and COVID-19–related ICU admission (35.6% [95% CI, 20.0%-48.3%]),” the researchers wrote. “Among 88, 17 persons with cancer (24 589 female individuals [27.8%]) with 81,027 person-years of follow-up during the bivalent period, patients who received this booster (38%) had a COVID-19 hospitalization rate of 13.4 per 1000 person-years vs 21.7 per 1000 person-years among persons who did not receive a bivalent vaccine, with an adjusted VE of 29.9% (95% CI, 19.4%-39.1%) and NNV to prevent 1 COVID-19 hospitalization of 451 (95% CI, 345-697); the adjusted VE was 30.1% (95% CI, 7.7%-47.0%) to prevent COVID-19–related ICU admission.”
The authors advised, however, that uptake of COVID-19 vaccine boosters was low, and “interventions are therefore justified to increase COVID-19 uptake in this high-risk population.”
Background information in the article pointed out that cancer patients, especially those receiving anticancer treatments, are at increased risk of severe illness and mortality from SARS-CoV-2 infection. In November 2021, the national Centers for Disease Control and Prevention recommended additional COVID-19 vaccine doses for immunocompromised individuals, including patients with cancer who had completed their primary vaccine series. Since then, annual vaccination with an additional dose after 6 months has been recommended for persons who are moderately or severely immunocompromised.
The authors explained that, because phase 3 COVID-19 vaccine trials excluded patients with cancer, “the initial evidence to support the administration of additional vaccine boosters for patients with cancer was derived predominantly from immunologic studies showing reduced immune responses in patients with cancer and observational studies of vaccine effectiveness (VE). These data showed suboptimal immune responses among patients with cancer who received the primary 2-dose vaccination schedule and lower VE and increased risk of COVID-19–related intensive care unit (ICU) admission and mortality.”
The situation has changed, however, according to the article. “With the transition of COVID-19 into an endemic disease, it is crucial to recognize that patients with cancer will be at a persistently heightened risk of severe illness, and therefore ongoing assessment of vaccination usage and outcomes remains vital for informing effective prevention efforts.”
The authors said the study had three key points:
- Despite widespread availability of COVID-19 vaccines, vaccine uptake was relatively low, with only 69% of persons with cancer receiving the recommended monovalent COVID-19 vaccine booster and only 38% received a bivalent COVID-19 vaccine.
- The overall VE for prevention of COVID-19 hospitalization for the monovalent booster (29.2%) and the bivalent vaccine (29.9%) were similar, with low NNV (166 for monovalent booster; 451 for bivalent vaccine).
- Although overall VE among cancer patientscompared with nonimmunocompromised persons was either lower (29.2% vs 50.8% for the monovalent booster, respectively) or similar (29.9% vs 30.1% for the bivalent vaccine, respectively) the NNV to prevent one COVID-19 hospitalization was substantially lower (166 for persons with cancer vs. 1,107 for nonimmunocompromised persons for the monovalent booster; 451 vs. 4,503 for the bivalent vaccine), due to substantially higher baseline rates of COVID-19 hospitalization among persons with cancer.
The researchers suggested that VE studies should take into account the diverse characteristics of patients and their disease conditions, including primary tumor site, stage of disease, treatment regimen, underlying medical conditions, and demographic factors, such as age and sex.
- Skarbinski J, et al. COVID-19 Vaccine Booster Uptake and Effectiveness Among US Adults With Cancer. JAMA Oncol. doi:10.1001/jamaoncol.2025.2020. Published online July 17, 2025.