The BNT162b2 vaccine is associated with lower new COVID-19 cases in nursing home residents and staff

Abstract

Background/objectives: The effectiveness of the BNT162b2 vaccine on preventing the spread of COVID-19 and deaths in nursing homes (NH) is unknown.

Design: We used zero-inflated negative binomial mixed effects regressions to model the associations of time since the vaccine clinic ending the week of December 27, 2020 (cohort 1), January 3, 2021 (cohort 2), or January 10, 2021 (cohort 3) controlling for county rate of COVID-19, bed size, urban location, racial and ethnic census, and level of registered nurses with resident cases and deaths of COVID-19 and staff cases of COVID-19.

Setting and participants: All 2501 NHs who held a vaccine clinic from the first 17 states to initiate clinics as part of the Pharmacy Partnership for Long-Term Care Program.

Main outcome(s) and measure(s): Adjusted Incidence Rate Ratio (IRR) for time in 3, 4, 5, and 6 weeks after the first vaccine clinic for resident cases and deaths of COVID-19 and staff cases of COVID-19.

Results: Resident and staff cases trended downward in all three cohorts following the vaccine clinics. Time following the first clinic at 5 and 6 weeks was consistently associated with fewer resident cases (IRR: 0.68 [95% CI: 0.54-0.84], IRR: 0.64 [95% CI: 0.48-0.86], respectively); resident deaths (IRR: 0.59 [95% CI: 0.45-0.77], IRR: 0.45 [95% CI: 0.31-0.65], respectively); and staff cases (IRR: 0.64 [95% CI: 0.56-0.73], IRR: 0.51 [95% CI: 0.42-0.62], respectively). Other factors associated with fewer resident and staff cases included facilities with less than 50 certified beds and high nurse staffing per resident day (>0.987). Contrary to prior research, higher Hispanic non-white resident census was associated with fewer resident cases (IRR: 0.42, 95% CI: 0.31-0.56) and deaths (IRR: 0.18, 95% CI: 0.12-0.27).

Conclusions: The BNT162b2 vaccine is associated with decreased spread of SARS-CoV-2 in both residents and staff as well as decreased deaths among residents.

Keywords: BNT162b2; COVID-19; SARS-CoV-2; health care worker; mortality; nursing home; vaccination.

FIGURE 1

Unadjusted trends in resident and staff COVID‐19 cases and resident deaths from December 20, 2020, to February 7, 2021. Panel A, Resident COVID‐19 Cases per 1000 Residents‐Weeks. Panel B, Resident COVID‐19 Death per 1000 Residents‐Weeks. Panel C, Staff COVID‐19 Cases per 1000 FTE Clinical Staff‐Weeks. We divided SNFs into three cohorts based on the week in which they held their first vaccine clinic: Blue Line: Cohort 1 (vaccine clinics ending 12/27/2020, n = 840); Red Line: Cohort 2 (vaccine clinics ending 1/3/2021, n = 830); Green Line: Cohort 3 (vaccine clinics ending 1/10/2021, n = 831). Panel A, The unadjusted rate of COVID cases was stable in all three cohorts up until the week ending January 17th, 2021 when resident case of COVID‐19 began to decrease each week for all three cohorts. Panel B, The unadjusted resident COVID‐19 death was relatively stable and began to decline in all three cohorts starting the week ending January 24, 2021. Panel C, Depicts the trend in unadjusted staff Cases of COVID‐19 that were increasing through the end of January 10 but then began to decrease for SNFs in the blue and red cohorts, with the decline in cases lagging for the green cohort

FIGURE 2

Resident COVID‐19 Cases and Deaths Incidence Rate Ratio from the Zero Inflated Negative Binomial Model. The incident rate ratio (IRR) with 95 confidence intervals in green depicts IRR whose 95% CI are less than 1.0 indicating an association with having fewer resident COVID‐19 cases or deaths. Low resident minority and low Hispanic, non‐white census, medium RN staffing level, and medium bed size were the referent groups. When controlling for all these variables that might explain trends in resident cases or deaths, time from the clinic was associated with fewer cases and deaths and had a stronger association as more time elapsed from the first clinic. In addition, time in calendar weeks was associated with fewer resident cases but not deaths corresponding to the general decline in cases seen nationally. Small facilities (less than 50 certified beds) and those with high Hispanic non‐white census were less likely to have resident cases and deaths. For resident deaths, higher nursing hours were also associated with less deaths

FIGURE 3

Staff COVID‐19 Cases Incidence Rate Ratio from the Zero Inflated Negative Binomial Model. The incident rate ratio (IRR) with 95 confidence intervals in green depicts IRR that is less than 1.0 indicating an association with having fewer resident COVID‐19 cases or deaths and IRRs in red indicate where 95% CI was greater than 1.0. Low resident minority and low Hispanic, non‐white census, medium RN staffing level, and medium bed size were the referent groups. When controlling for all these variables that might explain trends in resident cases of deaths, time from the clinic was associated with fewer staff cases and had a stronger association as more time elapsed from the first clinic. In addition, time in weeks was associated with more cases as was facilities with medium census of racial minorities compared with low census. However, facilities with higher Hispanic non‐white census were associated with fewer staff cases as were facilities with high nursing staffing levels