The Efficacy of COVID-19 Vaccination in Mortality Among Multi-Ethnic Long-Term Care Residents in New Zealand.

OBJECTIVE

Older adults faced heightened vulnerability during the COVID-19 pandemic, leading to increased mortality. This study investigated the impact of COVID-19 vaccination on COVID-19-related mortality among the main ethnic groups in long-term care during the Delta-Omicron wave in New Zealand.

METHODS

We used national health datasets (interRAI Long Term Care Facility, COVID-19 immunisation, COVID-19 test results, mortality) from August 2021 to August 2022. Multi-state modelling assessed transition hazards from infection to COVID death and other causes of death among Māori, Pacific, Asian and European residents. Transition hazard ratios compared the risk of transitioning from infection to COVID versus non-COVID death.

RESULTS

A total of 34,147 long-term care residents (female: 64.0%, mean age: 84.8 years SD = 8.5) were included. For Māori aged < 85, Asians < 63 and Europeans < 93 who had 3+ doses of vaccine, the risk of COVID death was statistically lower than non-COVID death. Unvaccinated residents showed higher hazards for transitioning to COVID death. For Pacific peoples, transition hazard ratios were not statistically significant, likely due to small sample size. However, successive vaccine doses suggested reduced COVID mortality.

CONCLUSIONS

COVID-19 vaccination reduced the risk of COVID deaths across ethnicities in New Zealand's long-term care. However, the level of protection offered by the vaccine varied by ethnicity and age.