Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Quebec, Canada.
Sainte-Justine Hospital Health and Research Center, Montreal, Quebec, Canada.
Influenza Other Respir Viruses. 2022 Sep;16(5):916-925. doi: 10.1111/irv.12997. Epub 2022 May 5.
Understanding the immune response to natural infection by SARS-CoV-2 is key to pandemic management, especially in the current context of emerging variants. Uncertainty remains regarding the efficacy and duration of natural immunity against reinfection.
We conducted an observational prospective cohort study in Canadian healthcare workers (HCWs) with a history of PCR-confirmed SARS-CoV-2 infection to (i) measure the average incidence rate of reinfection and (ii) describe the serological immune response to the primary infection.
Our cohort comprised 569 HCWs; median duration of individual follow-up was 371 days. We detected six cases of reinfection in absence of vaccination between August 21, 2020, and March 1, 2022, for a reinfection incidence rate of 4.0 per 100 person-years. Median duration of seropositivity was 415 days in symptomatics at primary infection compared with 213 days in asymptomatics (p < 0.0001). Other characteristics associated with prolonged seropositivity for IgG against the spike protein included age over 55 years, obesity, and non-Caucasian ethnicity.
Among unvaccinated healthcare workers, reinfection with SARS-CoV-2 following a primary infection remained rare.
了解 SARS-CoV-2 自然感染引起的免疫反应是大流行管理的关键，尤其是在当前新兴变异株的背景下。人们对自然免疫对再次感染的效力和持续时间仍存在不确定性。
我们对有 PCR 确诊 SARS-CoV-2 感染史的加拿大医护人员进行了一项观察性前瞻性队列研究，以（i）测量再次感染的平均发生率，以及（ii）描述初次感染的血清学免疫反应。
我们的队列包括 569 名医护人员；个体随访的中位时间为 371 天。在 2020 年 8 月 21 日至 2022 年 3 月 1 日期间，在未接种疫苗的情况下，我们检测到 6 例再感染病例，再感染发病率为每 100 人年 4.0 例。与无症状感染者相比，有症状感染者初次感染时 IgG 对刺突蛋白的血清阳性中位持续时间为 415 天，而无症状感染者为 213 天（p<0.0001）。与 IgG 针对刺突蛋白的持续血清阳性相关的其他特征包括年龄超过 55 岁、肥胖和非白种人种族。
在未接种疫苗的医护人员中，SARS-CoV-2 再次感染在初次感染后仍然很少见。
