Influenza vaccination can be modestly effective in reducing laboratory-confirmed influenza-associated hospitalizations in people with chronic obstructive pulmonary disease (COPD), according to a study published in The Journal of Infectious Diseases.

Researchers in Ontario, Canada, sought to determine seasonal influenza vaccine effectiveness against laboratory-confirmed influenza-associated hospitalizations among older adults (aged ≥66 years) with COPD using health administrative data and respiratory specimens collected during the 2010 to 2011 and 2015 to 2016 influenza seasons. They found that receipt of seasonal influenza vaccine was associated with an adjusted 22% reduction in laboratory-confirmed influenza-associated hospitalization.

However, when adjusting for potential misclassification of vaccination status, this reduction in hospitalizations increased to 43%, which is very similar to that found in older adults without COPD. In addition, the researchers found that vaccine effectiveness did not vary by most patient, specimen collection, or influenza season characteristics, with the exception of prior season influenza vaccination, which seemed to lower vaccine effectiveness.

Study limitations should be noted, including the observational design, which was susceptible to unmeasured confounding and the potential for misclassification of influenza vaccination status. Because a large pragmatic randomized controlled trial evaluating influenza vaccination would be unethical, this is likely the most robust estimate of vaccine effectiveness for hospitalizations in the COPD population to guide influenza vaccination recommendations for these patients.

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The authors concluded that, “Vaccination remains the most effective tool to decrease influenza-associated morbidity and mortality; however, the imperfect effectiveness observed emphasizes the need for more effective influenza vaccines for older patients combined with other preventive strategies.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Gershon AS, Chung H, Porter J, et al. Influenza vaccine effectiveness in preventing hospitalizations in older patients with chronic obstructive pulmonary disease [published online September 24, 2019]. J Infect Dis. doi:10.1093/infdis/jiz419