Estimates of the burden of severe acute respiratory syndrome coronavirus 2 reinfections are limited by the scarcity of population-level studies incorporating genomic support. We conducted a systematic study of reinfections in Madrid, Spain, supported by genomic viral analysis and host genetic analysis, to cleanse laboratory errors and to discriminate between reinfections and recurrences involving the same strain. Among the 41,195 cases diagnosed (March 2020–March 2021), 93 (0.23%) had 2 positive reverse transcription PCR tests (55–346 days apart). After eliminating cases with specimens not stored, of suboptimal sequence quality, or belonging to different persons, we obtained valid data from 22 cases. Of those, 4 (0.01%) cases were recurrences involving the same strain; case-patients were 39–93 years of age, and 3 were immunosuppressed. Eighteen (0.04%) cases were reinfections; patients were 19–84 years of age, and most had no relevant clinical history. The second episode was more severe in 8 cases.

由于缺乏纳入基因组支持的人群水平研究，对严重急性呼吸综合征冠状病毒 2 型再感染负担的估计受到限制。我们在基因组病毒分析和宿主遗传分析的支持下，对西班牙马德里的再感染进行了系统研究，以消除实验室错误并区分涉及同一菌株的再感染和复发。在确诊的 41,195 例病例中（2020 年 3 月至 2021 年 3 月），93 例（0.23%）有 2 次逆转录 PCR 检测呈阳性（间隔 55-346 天）。在排除样本未保存、序列质量次优或属于不同人的病例后，我们从22个病例中获得了有效数据。其中，4例（0.01%）为同一菌株复发；病例患者年龄39-93岁，其中3例免疫抑制。18例（0.04%）再次感染；患者年龄在19-84岁之间，大多数没有相关临床病史。第二次发作较严重者8例。