新型冠状病毒（简称新冠病毒）感染者排毒是一个连续动态过程,根据排毒特征可分为潜隐期、排毒初期、排毒高峰期和衰减期。感染新冠病毒后,感染者一般在前1~3 d处于潜隐期,表现为连续的核酸检测结果为阴性,这一时期没有传染性,密切接触者感染风险很低;排毒初期表现为短时间内核酸检测Ct值快速下降,临床症状逐渐显现。感染者在这一时期的传染性逐渐上升,其密切接触者感染的风险也逐渐增加,但尚处于感染早期,排毒可能性低,次级密切接触者感染风险低;排毒高峰表现为核酸检测Ct值维持低水平,临床症状明显。这一时期感染者传染性最强,接触者感染风险最高,应适当扩大密切接触者判定范围;衰减期表现为核酸检测Ct值逐渐升高,临床症状逐渐消失。这一时期感染者传染性逐渐下降至消失。在一起暴发疫情中,处于衰减期的感染者更可能是传播链中的早期感染者。如果在无新型冠状病毒肺炎流行的地区发现衰减期感染者,则提示当地疫情已有一段时间的传播,规模可能较大。根据排毒特征可以更加科学、精确地判定风险人员,在最大限度控制风险的同时减少防疫资源的浪费。

Viral shedding of SARS-CoV-2 is a continuous dynamic process, which can be divided into latent stage, initial stage, peak stage and decreasing stage according to the characteristics of viral shedding. After being infected with SARS-CoV-2, the infected person generally stays in the latent period for 1-3 days, which is characterized by continuous negative nucleic acid test results and no infectiousness, and the risk of infection for close contacts is very low. At the initial stage of viral shedding is characterized by a rapid decline in the Ct value of nucleic acid tests in a short time, and clinical symptoms gradually appear. The infectiousness of the infected person gradually increases during this period, and the risk of infection for close contacts also gradually increases, but it is still in the early stage of infection, the possibility of viral shedding is low, and the risk of infection of secondary close contacts is low. The peak of viral shedding is characterized by low Ct value in nucleic acid test and obvious clinical symptoms;during this period, the infected person is the most infectious, and the risk of infection of the contact is the highest, so the scope of close contacts should be expanded appropriately. The decreasing period is characterized by the gradual increase of Ct value of nucleic acid test and the gradual disappearance of clinical symptoms; during this period, the infectiousness of the infected person gradually decreases to disappear. In an outbreak, an infected person in the decreasing phase is more likely to be an early infected person in the transmission chain. If infected individuals in the decreasing phase are found in an area without a SARS-CoV-2 epidemic, it suggests that the local outbreak epidemic has been spreading for some time and may be larger in scale. According to the characteristics of viral shedding, risk personnel can be determined more scientifically and accurately, so as to minimize the risk and reduce the waste of epidemic prevention resources.