- Influenza vaccination reduced laboratory-confirmed influenza-associated hospitalizations by 22%-43% in patients with COPD from the 2010-2011 to 2015-2015 seasons.
Why this matters
- Patients with COPD have higher risk of morbidity from influenza, but influenza vaccine effectiveness varies seasonally, and evidence in patients with COPD is limited.
- Test-negative study involving 21,748 adults aged ≥66 years with physician-diagnosed COPD who were hospitalized during the 2010-2011 to 2015-2016 influenza seasons in Ontario, Canada, and received a laboratory influenza test within 3 days before or during hospitalization.
- Influenza vaccination status determined from billing claims.
- 56% of population had influenza vaccination.
- 16.7% of adults tested positive for influenza, including 15.3% of vaccinated adults (n=12,174) and 18.6% of unvaccinated adults (n=9,574).
- Vaccination reduced odds of lab-confirmed influenza 22% (95% CI, 15%-27%) after covariate adjustment, similar to effectiveness in people without COPD.
- Second analysis corrected for potential misclassification of vaccination status: 43% effectiveness (95% CI, 35%-52%).
- Vaccine effectiveness did not vary significantly in subgroup analyses or by patient-, COPD-, or specimen collection-related factors.
- Use of laboratory-confirmed influenza may underestimate influenza incidence.
- Vaccination status undercaptured.
- Residual confounding possible.
- Subgroup analyses potentially underpowered.