Efficacy of trivalent seasonal influenza vaccination in reducing mortality and hospitalization in Chinese nursing home older adults

Objective: To examine the clinical efficacy of the trivalent seasonal influenza vaccination among Chinese older adults residing in a nursing home.

Design: A 12-month prospective cohort study. Participants were divided into 2 groups based on their own choice on vaccination of trivalent seasonal influenza vaccine: vaccinated group and unvaccinated group.

Setting: Fifty-eight nursing homes in Hong Kong.

Participants: A total of 1859 older adults residing in a nursing home.

Measurements: All-cause mortality, pneumonia-related mortality, all-cause hospitalization, and pneumonia-related hospitalization.

Results: A total of 1859 older adults residing in a nursing home were included: 1214 (65.3%) in the vaccinated group and 645 (34.7%) in the unvaccinated group. At 12 months of study, for all-cause mortality, 14.6% (177 of 1214) of the vaccinated group and 20.2% (130 of 645) of the unvaccinated group had died (P < .001). Multivariate analysis showed the hazard ratio for the vaccinated group was 0.72 (95% confidence interval [CI]: 0.54-0.95; P < .01). For pneumonia-related mortality, 9.4% (114 of 1214) of the vaccinated group and 12.7% (82 of 645) of the unvaccinated group died (P = .033). Multivariate analysis showed the hazard ratio for the vaccinated group was 0.80 (CI: 0.62-0.98; P < .05). The median number of all-cause hospitalizations per 1000 person-months was 55 (0-111) for the vaccinated group and 55 (0-167) for the unvaccinated group (P < .01). The median number of pneumonia-related hospitalizations per 1000 person-months was 0 (0-55) for the vaccinated group and 0 (0-111) for the unvaccinated group (P < .01).

Conclusions: Vaccination of trivalent seasonal influenza vaccine in Chinese nursing home older adults significantly reduced all-cause and pneumonia-related mortality and hospitalization.