Prevention of mortality and pneumonia among nursing home older adults by dual pneumococcal and seasonal influenza vaccination during a pandemic caused by novel pandemic influenza A (H1N1).

OBJECTIVE To evaluate the efficacy of dual vaccination of seasonal influenza and pneumococcus in nursing home older adults during a novel pandemic of influenza A (H1N1). SETTING Nine nursing homes in Hong Kong. PARTICIPANTS A total of 532 nursing home older adults were included in the study. MEASUREMENTS Efficacy of dual vaccination of seasonal influenza and pneumococcus in nursing home older adults during a novel pandemic influenza A (H1N1). DESIGN A prospective 12-month cohort study was conducted on older residents from December 2009 to November 2010. Participants were divided into 3 groups according to their choice of vaccination: received both seasonal influenza and 23-valent pneumococcal polysaccharide vaccine (PPV-TIV group), received seasonal influenza vaccine alone (TIV group), and those who refused both vaccinations (unvaccinated group). Those who had received vaccination for influenza A (H1N1) were excluded. Outcome measures included mortality from all causes, pneumonia, and vascular causes. RESULTS There were 246 in the PPV-TIV group, 211 in the TIV group, and 75 in the unvaccinated group. Baseline characteristics were similar among the groups. The 12-month mortality rates of the PPV-TIV, TIV alone group, and unvaccinated group were 17.1%, 27.0%, and 37.3% respectively (P < .001). Multivariate analysis demonstrated that, compared with vaccination of seasonal influenza alone, dual vaccination significantly reduced all-cause mortality (hazard ratio [HR] 0.54; 95% confidence interval [CI]: 0.35-0.84; P < .01), mortality from pneumonia (HR 0.60; 95% CI: 0.35-0.99; P < .05), and mortality from vascular causes (HR 0.24; 95% CI: 0.09-0.64; P < .01). CONCLUSIONS During an influenza pandemic or when the circulating influenza strain was not matched by the trivalent seasonal influenza vaccine, dual vaccination of influenza and pneumococcus provided additional protection to nursing home older adults in reducing mortality.