Association of COVID-19 Vaccination Rates of Staff and COVID-19 Illness and Death Among Residents and Staff in US Nursing Homes

Abstract

Importance: It is important to understand the association between staff vaccination rates and adverse COVID-19 outcomes in nursing homes.

Objective: To assess the extent to which staff vaccination was associated with preventing COVID-19 cases and deaths among residents and staff in nursing homes.

Design, setting, and participants: This longitudinal cohort study used data on COVID-19 outcomes in Medicare- and Medicaid-certified nursing homes in the US between May 30, 2021, and January 30, 2022. Participants included the residents of 15 042 US nursing homes that reported COVID-19 data to the Centers for Disease Control and Prevention and passed Centers for Medicare & Medicaid Services data quality checks in the National Healthcare Safety Network.

Exposures: Weekly staff vaccination rates.

Main outcomes and measures: Main outcomes are weekly COVID-19 cases and deaths among residents and weekly COVID-19 cases among staff. The treatment variable is the primary 2-dose staff vaccination rate in each facility each week.

Results: In the primary analysis of 15 042 nursing homes before the Omicron variant wave (May 30 to December 5, 2021) using fixed effects of facility and week, increasing weekly staff vaccination rates by 10 percentage points was associated with 0.13 (95% CI, -0.20 to -0.10) fewer weekly COVID-19 cases per 1000 residents, 0.02 (95% CI, -0.03 to -0.01) fewer weekly COVID-19 deaths per 1000 residents, and 0.03 (95% CI, -0.04 to -0.02) fewer weekly COVID-19 staff cases. In the secondary analysis of the Omicron wave (December 5, 2021, to January 30, 2022), increasing staff vaccination rates were not associated with lower rates of adverse COVID-19 outcomes in nursing homes.

Conclusions and relevance: The findings of this cohort study suggest that before the Omicron variant wave, increasing staff vaccination rates was associated with lower incidence of COVID-19 cases and deaths among residents and staff in US nursing homes. However, as newer, more infectious and transmissible variants of the virus emerged, the original 2-dose regimen of the COVID-19 vaccine as recommended in December 2020 was no longer associated with lower rates of adverse COVID-19 outcomes in nursing homes. Policy makers may want to consider longer-term policy options to increase the uptake of booster doses among staff in nursing homes.

Figure 1.. Unadjusted Associations Between Staff Vaccination Rates and COVID-19 Outcomes in Nursing Homes

A, Nursing homes (NHs) with a high proportion of vaccinated staff were in the top quartile (highest 25%) of staff vaccination rates; NHs with a low proportion of vaccinated staff were in the bottom quartile (lowest 25%) of staff vaccination rates. B, Quartiles of staff vaccination rates are calculated for each week and thereby vary for each week. C and D, Data represent facility-weeks between May 30 and December 5, 2021.

Figure 2.. Adjusted Associations Between Staff Vaccination Rates and Weekly COVID-19 Outcomes in Nursing Homes

A, Regressions controlled for facility and week fixed effects and adjust for resident, staff vaccination rates, county-level COVID-19 prevalence per 1000 population, and direct care staff hours per resident day. B and C, Data represent facility-weeks between May 30 and December 5, 2021.