From the Emory University Rollins School of Public Health, Atlanta, GA.
Fulton County Board of Health, Atlanta, GA.
Epidemiology. 2022 Sep 1;33(5):669-677. doi: 10.1097/EDE.0000000000001510. Epub 2022 May 19.
US long-term care facilities (LTCFs) have experienced a disproportionate burden of COVID-19 morbidity and mortality.
We examined SARS-CoV-2 transmission among residents and staff in 60 LTCFs in Fulton County, Georgia, from March 2020 to September 2021. Using the Wallinga-Teunis method to estimate the time-varying reproduction number, R(t), and linear-mixed regression models, we examined associations between case characteristics and R(t).
Case counts, outbreak size and duration, and R(t) declined rapidly and remained low after vaccines were first distributed to LTCFs in December 2020, despite increases in community incidence in summer 2021. Staff cases were more infectious than resident cases (average individual reproduction number, R i = 0.6 [95% confidence intervals [CI] = 0.4, 0.7] and 0.1 [95% CI = 0.1, 0.2], respectively). Unvaccinated resident cases were more infectious than vaccinated resident cases (R i = 0.5 [95% CI = 0.4, 0.6] and 0.2 [95% CI = 0.0, 0.8], respectively), but estimates were imprecise.
COVID-19 vaccines slowed transmission and contributed to reduced caseload in LTCFs. However, due to data limitations, we were unable to determine whether breakthrough vaccinated cases were less infectious than unvaccinated cases. Staff cases were six times more infectious than resident cases, consistent with the hypothesis that staff were the primary drivers of SARS-CoV-2 transmission in LTCFs.
美国长期护理机构（LTCF）在 COVID-19 发病率和死亡率方面承受了不成比例的负担。
我们调查了 2020 年 3 月至 2021 年 9 月期间佐治亚州富尔顿县 60 家 LTCF 中居民和工作人员的 SARS-CoV-2 传播情况。我们使用 Wallinga-Teunis 方法估计时变繁殖数 R(t)，并使用线性混合回归模型，考察了病例特征与 R(t)之间的关系。
尽管 2021 年夏季社区发病率上升，但自 2020 年 12 月首次向 LTCF 分发疫苗以来，病例数、疫情规模和持续时间以及 R(t)迅速下降并保持低位。与居民病例相比，工作人员病例更具传染性（平均个体繁殖数，R i = 0.6 [95%置信区间[CI] = 0.4, 0.7]和 0.1 [95% CI = 0.1, 0.2]）。未接种疫苗的居民病例比接种疫苗的居民病例更具传染性（R i = 0.5 [95% CI = 0.4, 0.6]和 0.2 [95% CI = 0.0, 0.8]），但估计值不够准确。
COVID-19 疫苗减缓了传播速度，并减少了 LTCF 的病例数。然而，由于数据限制，我们无法确定突破性接种病例是否比未接种病例的传染性更低。工作人员病例比居民病例传染性高出六倍，这与工作人员是 LTCF 中 SARS-CoV-2 传播主要驱动因素的假设一致。
