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.