Department of Epidemiology, National Institute of Health Doutor Ricardo Jorge, Lisbon, Portugal
Public Health Research Center, National School of Public Health, NOVA University of Lisbon, Lisbon, Portugal.
BMJ Open. 2023 May 2;13(5):e068996. doi: 10.1136/bmjopen-2022-068996.
Healthcare workers (HCWs) were the first to be prioritised for COVID-19 vaccination. This study aims to estimate the COVID-19 vaccine effectiveness (VE) against SARS-CoV-2 symptomatic infection among HCWs in Portuguese hospitals.
Prospective cohort study.
We analysed data from HCWs (all professional categories) from three central hospitals: one in the Lisbon and Tagus Valley region and two in the central region of mainland Portugal, between December 2020 and March 2022. VE against symptomatic SARS-CoV-2 infection was estimated as one minus the confounder adjusted HRs by Cox models considering age group, sex, self-reported chronic disease and occupational exposure to patients diagnosed with COVID-19 as adjustment variables.
During the 15 months of follow-up, the 3034 HCWs contributed a total of 3054 person-years at risk, and 581 SARS-CoV-2 events occurred. Most participants were already vaccinated with a booster dose (n=2653, 87%), some are vaccinated with only the primary scheme (n=369, 12.6%) and a few remained unvaccinated (n=12, 0.4%) at the end of the study period. VE against symptomatic infection was 63.6% (95% CI 22.6% to 82.9%) for HCWs vaccinated with two doses and 55.9% (95% CI -1.3% to 80.8%) for HCWs vaccinated with one booster dose. Point estimate VE was higher for individuals with two doses taken between 14 days and 98 days (VE=71.9%; 95% CI 32.3% to 88.3%).
This cohort study found a high COVID-19 VE against symptomatic SARS-CoV-2 infection in Portuguese HCWs after vaccination with one booster dose, even after Omicron variant occurrence. The small sample size, the high vaccine coverage, the very low number of unvaccinated individuals and the few events observed during the study period contributed to the low precision of the estimates.
医疗工作者（HCWs）是首批优先接种 COVID-19 疫苗的人群。本研究旨在评估葡萄牙医院 HCWs 中 COVID-19 疫苗对 SARS-CoV-2 症状性感染的疫苗有效性（VE）。
前瞻性队列研究。
我们分析了来自三家中心医院（一家位于里斯本和塔古斯河谷地区，两家位于葡萄牙大陆中部地区）的 HCWs（所有专业类别）的数据：这些数据收集于 2020 年 12 月至 2022 年 3 月之间。通过 Cox 模型估计 VE，针对症状性 SARS-CoV-2 感染，将年龄组、性别、自我报告的慢性疾病和接触 COVID-19 确诊患者的职业暴露作为调整变量，用调整后的 HR 计算 VE。
在 15 个月的随访期间，3034 名 HCWs 共贡献了 3054 人年的风险，发生了 581 例 SARS-CoV-2 事件。大多数参与者已经接种了加强针（n=2653，87%），一些人仅接种了初级方案（n=369，12.6%），少数人在研究结束时仍未接种（n=12，0.4%）。接种两剂疫苗的 HCWs 对症状性感染的 VE 为 63.6%（95%CI 22.6%至 82.9%），接种一剂加强针的 HCWs 为 55.9%（95%CI -1.3%至 80.8%）。接种两剂疫苗的个体在接种后 14 天至 98 天之间的 VE 点估计值更高（VE=71.9%；95%CI 32.3%至 88.3%）。
本队列研究发现，在葡萄牙 HCWs 中，即使在 Omicron 变异株出现后，接种一剂加强针也能对 SARS-CoV-2 症状性感染产生较高的 COVID-19 VE。研究期间，由于样本量小、疫苗接种率高、未接种人群数量少以及观察到的事件数量少，导致估计值的精度较低。
