The 23-valent pneumococcal polysaccharide vaccine is effective in elderly adults over 75 years old--Taiwan's PPV vaccination program.

BACKGROUND

Pneumococcal infection is a serious cause of mortality and morbidity in the elderly. A nationwide pneumococcal polysaccharide vaccine (PPV) program for elderly adults aged 75 years and older was conducted in Taiwan in 2008. The efficacy of the PPV in this very elderly population was evaluated.

METHODS

The data were analyzed using the Taiwan National Health Insurance Research Database (NHIRD), the cause-of-death registration database and the invasive pneumococcal disease (IPD) notification database of Taiwan's Ministry of Health and Welfare. The efficacy of PPV administration in this very elderly population was evaluated using multivariate logistic regression after propensity score matching (PSM). The rates of IPD, death from IPD, pneumonia hospitalization, death from pneumonia, and all-cause mortality were compared for those who did and did not receive the PPV.

RESULTS

Among the 1078,955 eligible people, 318,257 (29.5%) received the PPV, and 760,698 (70.5%) were not vaccinated. Using PSM to adjust for confounding factors, including age, gender, influenza vaccination status, associated chronic diseases and health care utilization, those who received the PPV had significantly lower odds ratios (ORs) for IPD (OR=0.24, 95% CI=0.123-0.461, p<0.001), death from IPD (OR=0.09, 95% CI=0.011-0.704, p<0.022, p<0.001), pneumonia hospitalization (OR=0.40, 95% CI=0.395-0.415, p<0.001), death from pneumonia (OR=0.07, 95% CI=0.059-0.082, p<0.001), and all-cause mortality (OR=0.07, 95% CI=0.069-0.072, p<0.001) compared with those who were not vaccinated.

CONCLUSIONS

PPV vaccination in the previous year was associated with a 60% reduction in pneumonia hospitalization, a 76% reduction in IPD, and a greater than 90% reduction in death from pneumonia, IPD and all causes among people over 75 years old in Taiwan. Data from subsequent years in Taiwan and similar populations elsewhere are needed to evaluate the contribution of underlying variations in the mortality rate and the confounding effects of prior disease severity to these findings.