Additive Benefits of Pneumococcal and Influenza Vaccines among Elderly Persons Aged 75 Years or Older in Taiwan - A representative population- based comparative study

Objective: The answer to the question whether pneumococcal vaccine provides additional protection to the elderly who has already vaccinated with influenza vaccine remains inconclusive. This retrospective cohort study aimed to assess the additive effect of pneumococcal and influenza vaccines on the risk of mortality, hospitalization, and inpatient expenditure in the elderly aged 75 years or older in Taiwan. Methods: Data were extracted from the National Health Insurance claims data of a nationally representative elderly sample. To reduce potential selection bias, we employed a propensity score matching method to classify the vaccination status into 3 groups. Multivariable logistic and linear regression models were used to compare the outcomes among different vaccination groups. Results: The results indicated that vaccinated elderly had significantly lower all-cause mortality than non-vaccinated elderly. An additive effect of receiving both vaccines was associated with a significant 21% -28% reduction in the risk of hospitalization for respiratory conditions, COPD, CHF, and all diseases when compared with receiving influenza vaccine alone. Compared with receiving only the influenza vaccine, receiving both vaccines was associated with sizable 5%- 13% reductions in inpatient expenditures. Conclusions: This study confirmed that vaccination of elderly individuals with pneumococcal vaccine and influenza vaccine concomitantly has substantial beneficial effects.