COVID-19 vaccine effectiveness in patients with lung cancer: challenges in the Omicron era

Our plain-English summary of COVID-19 vaccine effectiveness in patients with lung cancer: challenges in the Omicron era, by S.M. Hosseini-Moghaddam, S. Swayze, J.C. Kwong, et al (BMC Infectious Diseases, 2026).

The study

• Authors: S.M. Hosseini-Moghaddam, S. Swayze, J.C. Kwong, F.A. Shepherd
• Journal: BMC Infectious Diseases
• Published: 2026;26(1)
• Read it: PubMed · Publisher · Free full text

Abstract

BACKGROUND: During the Omicron era, COVID-19 vaccines demonstrated over 90% effectiveness against severe disease in the general population. However, vaccine effectiveness (VE) in patients with lung cancer, who are at high risk for severe COVID-19, has not been well characterized. METHODS: In this population-based cohort, we employed a test-negative design using linked data from the Ontario Cancer Registry, health administrative databases, and the Ontario vaccination registry. We included all patients with active lung cancer or mesothelioma residing in Ontario, Canada, who were symptomatic and underwent SARS-CoV-2 RT-PCR testing from January 2, 2022, to June 30, 2025. The outcome of interest was a severe outcome, defined as hospitalization within 14 days or death within 30 days following SARS-CoV-2 test. We constructed an analytic cohort that included the earliest testing episode among test-positive and test-negative patients with severe outcomes. We also performed a sensitivity analysis comparing test-positive patients with severe outcomes to randomly selected testing episodes among test-negative patients. RESULTS: Among 47,344 tested patients, 3,332 (7.0%) were SARS-CoV-2 test-positive, of whom 1,967 (59%) experienced severe outcomes; 16,257 test-negative patients also developed severe outcomes. Adjusted VE against severe COVID-19 was 52% (95% CI: 42%, 60%) within 7–179 days post-vaccination, declining to 16% (95%CI: 0%, 30%) thereafter. In sensitivity analyses comparing 1,967 test-positive patients with severe outcomes to 18,922 randomly selected test-negative patients, adjusted VE was 49% (95% CI: 39%, 58%), declining to 12% (95% CI: −4% 26%) thereafter. CONCLUSIONS: In this large population-based study of patients with lung cancer and mesothelioma, COVID-19 vaccination was associated with moderate protection against severe outcomes, including hospitalization and death. These findings emphasize the importance of optimizing alternative preventive strategies, such as masking, social distancing, ensuring household and caregiver vaccinations, and improving post-infection management through early antiviral therapy and close monitoring for severe disease. CLINICAL TRIAL NUMBER: Not applicable.

In plain English

This study estimated how well COVID-19 vaccines protected adults with active lung cancer or mesothelioma in Ontario, Canada, against severe COVID-19 during the Omicron period. It did not study asbestos exposure and did not report results separately for mesothelioma. Using linked provincial registries and a test-negative design, the authors looked at patients tested for the virus between January 2, 2022, and June 30, 2025. They compared 1,967 test-positive patients who were hospitalized or died with 16,257 test-negative patients who were also hospitalized or died. After adjustment, vaccine effectiveness against severe COVID-19 was 52% (95% CI 42% to 60%) for patients vaccinated 7 to 179 days before testing. It was 16% (95% CI 0% to 30%) for those 180 days or more past their last dose. A sensitivity analysis gave 49% (39% to 58%) and 12% (minus 4% to 26%). In the compared group, 31.7% of test-positive and 19.6% of test-negative patients died. The authors concluded that vaccination was associated with moderate protection. They noted that they could not determine the exact cause of hospitalization or death, and that data on the type and duration of cancer treatment were not available.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Population-based test-negative design study (analogous to a nested case-control design) using linked registry and health administrative data
• Who was studied: Adults aged 18 or older in Ontario, Canada, with active lung cancer or mesothelioma diagnosed before December 31, 2024, who had SARS-CoV-2 RT-PCR testing from January 2, 2022, to June 30, 2025. After exclusions there were 3,332 test-positive and 44,012 test-negative patients. The main comparison was 1,967 test-positive patients with severe outcomes against 16,257 test-negative patients with severe outcomes.
• Exposure: COVID-19 vaccination, taken from the provincial COVaxON registry. Patients were classed as vaccinated 7 to 179 days before testing, 180 days or more before testing, or unvaccinated. No asbestos or fiber exposure was studied.
• Main results:
  • Primary analysis: adjusted vaccine effectiveness against severe COVID-19 (hospitalization within 14 days or death within 30 days) was 52% (95% CI: 42%, 60%) for patients vaccinated 7 to 179 days before testing. It was 16% (95% CI: 0%, 30%) for patients 180 days or more after their most recent dose.
  • Sensitivity analysis comparing the 1,967 test-positive patients with 18,922 randomly selected test-negative patients: adjusted vaccine effectiveness was 49% (95% CI: 39%, 58%). It was 12% (95% CI: minus 4%, 26%) for patients 180 days or more after their most recent dose.
  • In the sensitivity analysis, the text reports adjusted seasonal vaccine effectiveness of 43% (95% CI: 36%, 49%) and adjusted relative vaccine effectiveness of 42% (95% CI: 34%, 48%).
  • In the primary cohort, 623 (31.7%) of the test-positive patients and 3,189 (19.6%) of the test-negative patients died (p less than 0.001).
• The authors' conclusion: The authors concluded that, in patients with lung cancer and mesothelioma, COVID-19 vaccination was associated with moderate protection against severe outcomes, including hospitalization and death.
• Limitations the authors state:
  • The outcome was all-cause hospitalization or death linked to a positive test, and the exact cause of hospitalization or death could not be determined.
  • Data on cancer treatment type and duration, which could affect vaccine effectiveness and COVID-19 outcomes, were not available.
  • The databases lacked symptom-level detail and could not show whether symptoms came from the cancer or from SARS-CoV-2 infection.
  • For relative vaccine effectiveness, the reference group was people vaccinated 180 days or more earlier. This group had waning protection and varied in how much immunity remained.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Lung Cancer, Cancer Registry, Mesothelioma, Clinical Trial.

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