Trunfio Mattia, Verga Federica, Ghisetti Valeria, Burdino Elisa, Emanuele Teresa, Bonora Stefano, Di Perri Giovanni, Calcagno Andrea
Unit of Infectious Diseases, Department of Medical Sciences, Amedeo di Savoia Hospital, University of Torino, Corso Svizzera 164, 10159 Torino, Italy.
Occupational Medicine Unit, Maria Vittoria Hospital, 10159 Torino, Italy.
Vaccines (Basel). 2021 Nov 23;9(12):1377. doi: 10.3390/vaccines9121377.
We evaluated the clinical protection of BNT162b2 mRNA vaccine in healthcare workers (HCWs) and how COVID-19 manifestations and contagiousness change as the time since first dose increases. A matched (1:2 ratio) parallel cohort study was performed. During the first three months of vaccination campaign, HCWs of the entire health district ASL Città di Torino (Turin, Italy) were classified according to SARS-CoV-2-positivity in respect of the vaccination schedule: post-first-dose (fHCWs, <12 days), partially (PHCWs, ≥12 from first dose to ≤7 days after the second), and totally vaccinated (THCWs, ≥8 days after the second dose). Age-/sex-matched unvaccinated controls were randomly selected from all the SARS-CoV-2-positivity detected in the same district and period. Previous infections were excluded. Clinical and virologic data (ORF1ab gene cycle threshold values, Ct) were recorded. In total, 6800 HCWs received at least one dose, and 55 tested positive subsequently: 20 fHCWs, 25 PHCWs, 10 THCWs. Furthermore, 21.8% of breakthrough infections were in male, with a median age of 49 years (32-56), and 51.4% occurred while SARS-CoV-2 B.1.1.7 variant was predominant. The incident relative risk was 0.13 (0.12-0.15) for PHCWs and 0.06 (0.05-0.07) for THCWs. Compared to controls ( = 110), no difference was observed in fHCWs, while PHCWs and THCWs showed higher prevalence of asymptomatic infections, fewer signs/symptoms with a milder systemic involvement, and significantly higher Ct values (PHCWs 30.3 (24.1-35.5) vs. 22.3 (19.6-30.6), = 0.023; THCWs 35.0 (31.3-35.9) vs. 22.5 (18.2-30.6), = 0.024). Duration of symptoms was also shorter in THCWs (5 days (3-6) vs. 9 (7-14), = 0.028). A linear increase of 3.81 points in Ct values was observed across the groups by vaccination status ( = 0.001) after adjusting for age, sex, comorbidities, and time between COVID-19 onset and swab collection. BNT162b2 decreased the risk of PCR-confirmed infections and severe disease, and was associated with a virologic picture of lesser epidemiologic concern as soon as 12 days after the first vaccine dose.
我们评估了BNT162b2 mRNA疫苗对医护人员（HCW）的临床保护作用，以及自第一剂接种后随着时间推移，新冠病毒疾病（COVID-19）的表现和传染性如何变化。我们进行了一项匹配（1:2比例）的平行队列研究。在疫苗接种活动的前三个月，意大利都灵市ASL整个卫生区的医护人员根据接种时间表按新冠病毒2型（SARS-CoV-2）阳性情况进行分类：第一剂接种后（fHCW，<12天）、部分接种（PHCW，第一剂接种后≥12天至第二剂接种后≤7天）和完全接种（THCW，第二剂接种后≥8天）。年龄和性别匹配的未接种对照从同一地区和时期检测到的所有SARS-CoV-2阳性者中随机选取。排除既往感染情况。记录临床和病毒学数据（开放阅读框1ab基因循环阈值，Ct）。共有6800名医护人员接受了至少一剂疫苗，随后55人检测呈阳性：20名fHCW，25名PHCW，10名THCW。此外，21.8%的突破性感染发生在男性，中位年龄为49岁（32 - 56岁），51.4%的感染发生在SARS-CoV-2 B.1.1.7变异株占主导期间。部分接种医护人员的发病相对风险为0.13（0.12 - 0.15），完全接种医护人员为0.06（0.05 - 0.07）。与对照组（n = 110）相比，第一剂接种后医护人员未观察到差异，而部分接种和完全接种医护人员无症状感染的患病率更高，体征/症状更少，全身受累更轻，且Ct值显著更高（部分接种医护人员30.3（24.1 - 35.5）对22.3（19.6 - 30.6），P = 0.023；完全接种医护人员35.0（31.3 - 35.9）对22.5（18.2 - 30.6），P = 0.024）。完全接种医护人员的症状持续时间也更短（5天（3 - 6天）对9天（7 - 周），P = 0.028）。在调整年龄、性别、合并症以及COVID-19发病与拭子采集之间的时间后，根据疫苗接种状态，各组的Ct值呈线性增加3.81个点（P = 0.001）。BNT162b2降低了PCR确诊感染和重症疾病的风险，并且在第一剂疫苗接种后仅12天就与流行病学关注程度较低的病毒学情况相关。
