Division of General Internal Medicine, Geneva University Hospitals, Geneva, Switzerland.
Division of Primary Care Medicine, Geneva University Hospitals, Geneva, Switzerland.
Clin Infect Dis. 2022 Mar 1;74(4):622-629. doi: 10.1093/cid/ciab495.
Serological assays detecting anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies are being widely deployed in studies and clinical practice. However, the duration and effectiveness of the protection conferred by the immune response remains to be assessed in population-based samples. To estimate the incidence of newly acquired SARS-CoV-2 infections in seropositive individuals as compared to seronegative controls, we conducted a retrospective longitudinal matched study.
A seroprevalence survey including a representative sample of the population was conducted in Geneva, Switzerland, between April and June 2020, immediately after the first pandemic wave. Seropositive participants were matched one-to-two to seronegative controls, using a propensity-score including age, gender, immunodeficiency, body mass index (BMI), smoking status, and education level. Each individual was linked to a state-registry of SARS-CoV-2 infections. Our primary outcome was confirmed infections occurring from serological status assessment to the end of the second pandemic wave (January 2021).
Among 8344 serosurvey participants, 498 seropositive individuals were selected and matched with 996 seronegative controls. After a mean follow-up of 35.6 (standard deviation [SD] 3.2) weeks, 7 out of 498 (1.4%) seropositive subjects had a positive SARS-CoV-2 test, of whom 5 (1.0%) were classified as reinfections. In contrast, the infection rate was higher in seronegative individuals (15.5%, 154/996) during a similar follow-up period (mean 34.7 [SD 3.2] weeks), corresponding to a 94% (95% confidence interval [CI]: 86%- 98%, P < .001) reduction in the hazard of having a positive SARS-CoV-2 test for seropositives.
Seroconversion after SARS-CoV-2 infection confers protection against reinfection lasting at least 8 months. These findings could help global health authorities establishing priority for vaccine allocation.
血清学检测抗严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）抗体的方法在研究和临床实践中得到了广泛应用。然而，在基于人群的样本中，免疫反应所提供的保护的持续时间和有效性仍有待评估。为了估计与血清学阴性对照相比，血清学阳性个体中新发 SARS-CoV-2 感染的发生率，我们进行了一项回顾性纵向匹配研究。
2020 年 4 月至 6 月，在瑞士日内瓦进行了一项包括人群代表性样本的血清流行率调查，这是在第一次大流行浪潮之后立即进行的。采用包含年龄、性别、免疫缺陷、体重指数（BMI）、吸烟状况和教育程度的倾向评分，将血清学阳性参与者与血清学阴性对照进行一对一或二对二匹配。每个人都与 SARS-CoV-2 感染的国家登记处相联系。我们的主要结局是从血清学状态评估到第二次大流行浪潮结束（2021 年 1 月）期间确诊的感染。
在 8344 名血清学调查参与者中，选择了 498 名血清学阳性者，并与 996 名血清学阴性者进行了匹配。平均随访 35.6（标准差 [SD] 3.2）周后，498 名血清学阳性者中有 7 人（1.4%）的 SARS-CoV-2 检测呈阳性，其中 5 人（1.0%）被归类为再感染。相比之下，在相似的随访期间，血清学阴性个体的感染率更高（15.5%，154/996）（平均 34.7 [SD 3.2] 周），血清学阳性者 SARS-CoV-2 检测呈阳性的风险降低了 94%（95%置信区间 [CI]：86%-98%，P<0.001）。
SARS-CoV-2 感染后的血清转化可提供至少 8 个月的免受再感染的保护。这些发现可以帮助全球卫生当局确定疫苗分配的优先级。
