Occupational Medicine, Cambridge Health Alliance, Harvard Medical School, Macht Building 427, 1493 Cambridge Street, Cambridge, MA, 02139, USA.
Department of Environmental Health, Harvard University T.H. Chan School of Public Health, Boston, MA, USA.
BMC Infect Dis. 2022 May 12;22(1):457. doi: 10.1186/s12879-022-07434-y.
Data on COVID-19 vaccine effectiveness (VE) among healthcare workers (HCWs) during periods of delta variant predominance are limited.
We followed a population of urban Massachusetts HCWs (45% non-White) subject to epidemiologic surveillance. We accounted for covariates such as demographics and community background infection incidence, as well as information bias regarding COVID-19 diagnosis and vaccination status.
During the study period (December 16, 2020 to September 30, 2021), 4615 HCWs contributed to a total of 1,152,486 person-days at risk (excluding 309 HCWs with prior infection) and had a COVID-19 incidence rate of 5.2/10,000 (114 infections out of 219,842 person-days) for unvaccinated person-days and 0.6/10,000 (49 infections out of 830,084 person-days) for fully vaccinated person-days, resulting in an adjusted VE of 82.3% (95% CI 75.1-87.4%). For the secondary analysis limited to the period of delta variant predominance in Massachusetts (i.e., July 1 to September 30, 2021), we observed an adjusted VE of 76.5% (95% CI 40.9-90.6%). Independently, we found no re-infection among those with prior COVID-19, contributing to 74,557 re-infection-free person-days, adding to the evidence base for the robustness of naturally acquired immunity.
We found a VE of 76.5% against the delta variant. Our work also provides further evidence of naturally acquired immunity.
在德尔塔变异株占主导地位期间，关于医护人员（HCWs）的 COVID-19 疫苗有效性（VE）的数据有限。
我们对马萨诸塞州城市 HCWs（45%为非白人）进行了人群监测。我们考虑了人口统计学和社区背景感染发生率等协变量，以及 COVID-19 诊断和疫苗接种状况的信息偏倚。
在研究期间（2020 年 12 月 16 日至 2021 年 9 月 30 日），4615 名 HCWs 共为 1152486 人天（不包括 309 名有既往感染的 HCWs）承担风险，未接种疫苗者的 COVID-19 发病率为 5.2/10000（114 例感染/219842 人天），而完全接种疫苗者的发病率为 0.6/10000（49 例感染/830084 人天），调整后的 VE 为 82.3%（95%CI75.1-87.4%）。对于仅限于马萨诸塞州德尔塔变异株占主导地位期间（即 2021 年 7 月 1 日至 9 月 30 日）的二次分析，我们观察到调整后的 VE 为 76.5%（95%CI40.9-90.6%）。独立地，我们发现先前感染过 COVID-19 的人没有再次感染，从而增加了 74557 天无再感染的人天，为自然获得性免疫的稳健性提供了更多证据。
我们发现针对德尔塔变异株的 VE 为 76.5%。我们的工作还提供了自然获得性免疫的进一步证据。
