Syed Dr Mohamed Ahmed, Alnuaimi Dr Ahmed Sameer, A/Qotba Dr Hamda Abdulla
Department of Clinical Research, Directorate of Clinical Affairs, Primary Health Care Corporation, PO Box 26555, Doha, Qatar.
IJID Reg. 2022 Jun;3:21-23. doi: 10.1016/j.ijregi.2022.02.005. Epub 2022 Feb 15.
This aim of this study was to examine the relationship between severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seropositivity and subsequent infection.
A cohort study design was employed.
Stratified random sampling was undertaken to identify individuals aged 10 years and above registered with Qatar's largest primary healthcare provider. A questionnaire was administered, and blood samples were collected and analyzed for immunoglobulin G antibodies against SARS-CoV-2 at baseline. Participants were followed up until March 31, 2021 (a 34-week follow-up period) for vaccination status and a positive polymerase chain reaction (PCR) test for SARS-CoV-2.
A total of 2044 individuals participated in the study (97.2% of the planned sample). Of these, 185 (9%) were found to be seropositive at baseline. 450 individuals were vaccinated during the follow-up period - 246 with one dose and 204 with two doses. 86 (4.2%) individuals had a positive PCR test during the follow-up period, of which 80 (3.9%) were seronegative and six (0.3%) were seropositive (five undiluted and one with a titer ≥ 1:8).
Overall, the findings suggest that reinfections are uncommon. Antibody concentrations potentially influence the risk of subsequent infection. Therefore, it might not be necessary to subject seropositive individuals to vaccination and the quarantine policies that apply to seronegative individuals.
本研究旨在探讨严重急性呼吸综合征冠状病毒2（SARS-CoV-2）血清阳性与后续感染之间的关系。
采用队列研究设计。
采用分层随机抽样方法，确定在卡塔尔最大的初级医疗服务提供者处登记的10岁及以上个体。在基线时发放问卷，并采集血样分析抗SARS-CoV-2免疫球蛋白G抗体。对参与者进行随访，直至2021年3月31日（随访期为34周），了解疫苗接种情况以及SARS-CoV-2聚合酶链反应（PCR）检测结果是否为阳性。
共有2044人参与了本研究（占计划样本的97.2%）。其中，185人（9%）在基线时血清呈阳性。450人在随访期间接种了疫苗，其中246人接种了一剂，204人接种了两剂。86人（4.2%）在随访期间PCR检测呈阳性，其中80人（3.9%）血清呈阴性，6人（0.3%）血清呈阳性（5人未稀释，1人滴度≥1:8）。
总体而言，研究结果表明再次感染并不常见。抗体浓度可能会影响后续感染的风险。因此，可能没有必要让血清阳性个体接种疫苗以及实施适用于血清阴性个体的隔离政策。
