Effectiveness of influenza vaccination on in-hospital death in older adults with respiratory diseases.

Influenza vaccination is associated with lower risk of hospitalization outcomes among older adults with respiratory diseases, but there is limited evidence by disease subtypes and patients' characteristics. This study included patients aged ≥60 years hospitalized for respiratory diseases from the Beijing Urban Employee Basic Medical Insurance database during 6 influenza seasons. Vaccination status was assessed by linking with the Beijing Elderly Influenza Vaccination database. Multi-variable logistic regression was performed to calculate effect estimates. After adjusting for measured and unmeasured confounders, influenza vaccination was associated with a lower risk of in-hospital death among older adults hospitalized for respiratory diseases (odds ratio [95% confidence interval], 0.70 [0.62-0.80]). The protective association was observed among patients with chronic obstructive pulmonary disease (0.67 [0.47-0.98]) as well as those with pneumonia or influenza (0.77 [0.64-0.93]). The protective association was stronger in younger patients (0.59 [0.43-0.81] for <75 and 0.72 [0.63-0.83] for ≥75) and those with fewer comorbidities (0.49 [0.16-1.62] for 0, 0.65 [0.50-0.86] for 1-2, and 0.72 [0.63-0.83] for ≥3 comorbidities). Influenza vaccination was associated with lower risk of in-hospital death among older patients hospitalized for respiratory diseases, with stronger associations in patients with younger age and fewer comorbidities.