Can a patient diagnosed with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) be infected again? This question is still unsolved. We tried to analyze local and literature cases with a positive respiratory swab after recovery. We collected data from symptomatic patients diagnosed with SARS-CoV-2 infection in the Italian Umbria Region that, after recovery, were again positive for SARS-CoV-2 in respiratory tract specimens. Samples were also assessed for infectivity in vitro. A systematic review of similar cases reported in the literature was performed. The study population was composed of 9 patients during a 4-month study period. Among the new positive samples, six were inoculated in Vero-E6 cells and showed no growth and negative molecular test in culture supernatants. All patients were positive for IgG against SARS-CoV-2 nucleoprotein and/or S protein. Conducting a review of the literature, 1350 similar cases have been found. The presumptive reactivation occurred in 34.5 days on average (standard deviation, SD, 18.7 days) after COVID-19 onset, when the 5.6% of patients presented fever and the 27.6% symptoms. The outcome was favorable in 96.7% of patients, while the 1.1% of them were still hospitalized at the time of data collection and the 2.1% died. Several hypotheses have been formulated to explain new positive respiratory samples after confirmed negativity. According to this study, the phenomenon seems to be due to the prolonged detection of SARS-CoV-2 RNA traces in respiratory samples of recovered patients. The failure of the virus to replicate in vitro suggests its inability to replicate in vivo.

被诊断患有严重急性呼吸综合征冠状病毒-2 (SARS-CoV-2) 的患者会再次感染吗？这个问题仍然没有解决。我们尝试分析康复后呼吸道拭子呈阳性的当地病例和文献病例。我们收集了意大利翁布里亚地区诊断为 SARS-CoV-2 感染的有症状患者的数据，这些患者康复后，呼吸道标本中的 SARS-CoV-2 再次呈阳性。还评估了样品的体外感染性。对文献中报道的类似案例进行了系统回顾。研究人群由 4 个月研究期间的 9 名患者组成。新阳性样本中，有6例接种Vero-E6细胞，未见生长，培养上清液分子检测呈阴性。所有患者的 SARS-CoV-2 核蛋白 IgG 和/或 S 蛋白均呈阳性。查阅文献，发现类似案例1350个。推定的重新激活发生在 COVID-19 发病后平均 34.5 天（标准差，SD，18.7 天），其中 5.6% 的患者出现发烧，27.6% 的患者出现症状。96.7% 的患者结果良好，其中 1.1% 在数据收集时仍在住院，2.1% 死亡。人们提出了几种假设来解释在确认阴性后出现的新的阳性呼吸道样本。根据这项研究，这种现象似乎是由于在康复患者的呼吸道样本中长时间检测到 SARS-CoV-2 RNA 痕迹所致。病毒在体外无法复制表明其无法在体内复制。