The COVID-19 pandemic is a catastrophic global phenomenon, affecting human life in a way unseen since the 1918 influenza pandemic. Effective management of this threat requires halting transmission, a strategy requiring accurate knowledge of SARS-CoV-2 transmission patterns. This was a retrospective contact study aiming to estimate the transmission rate of COVID-19 by tracing contacts in symptomatic, pre-symptomatic, and asymptomatic patients. History of patients’ contacts during 24 h before appearance of symptoms or infection confirmation was traced for disease transmission. Overall, a total of 201 COVID-19 patients had contact with 7168 people in 24 h with an average of 35.66 contacts per patient, ranging from a minimum of 4 to maximum of 87 contacts (meetings). Out of 7168 persons met, infection was detected in 64 (0.89%). For the 155 symptomatic patients, a total of 5611 contacted persons were traced before appearance of symptoms (pre-symptomatic) in last 24 h with an average of 36.20 meetings per patient. The infection was transmitted in 63 (1.12%) people with 5548 (98.88%) remaining uninfected. Out of the 63 transmissions, 62 (98.4%) were traced within 6 h before symptom onset, while only 1 was identified in the 6–12 h timeframe before symptoms. A total of 1557 persons were traced having meeting/contacts with asymptomatic cases in last 24 h before infection confirmation. Out of these 1557 persons, only 1 was found to be infected and the infection rate was calculated to be 0.06%. Statistically, the transmission rate by pre-symptomatic patients was found to be significantly higher than the transmission rate by asymptomatic individuals (P < 0.05). In the studied population, the risk of pre-symptomatic and asymptomatic transmission of COVID-19 was low, with transmission risks of 1.12% and 0.06% respectively. Pre-symptomatic infection becomes very rare in contacts made longer than 6 h before onset of symptoms. The infection transmission is traced as long as about 9 h before the appearance of clear symptoms in the patients, but the incidence rate was as low as about 0.02% of the total contacts in that period.

中文翻译：

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AJK 中出现症状前和无症状患者的 COVID-19 传播频率：201 例病例的报告

COVID-19 大流行是一种灾难性的全球现象，以 1918 年流感大流行以来从未见过的方式影响着人类的生活。有效管理这一威胁需要阻止传播，这一策略需要准确了解 SARS-CoV-2 传播模式。这是一项回顾性接触研究，旨在通过追踪有症状、症状前和无症状患者的接触者来估计 COVID-19 的传播率。追踪患者出现症状或确诊感染前24小时内的接触史，以了解疾病传播情况。总体而言，共有 201 名 COVID-19 患者在 24 小时内与 7168 人接触，平均每名患者有 35.66 次接触，从最少 4 次到最多 87 次接触（会议）。在 7168 人中，64 人（0.89%）被检测出感染。在155名有症状患者中，过去24小时内共追踪到5611名症状出现前（症状前）接触者，平均每名患者会面36.20次。感染已在 63 人（1.12%）中传播，仍有 5548 人（98.88%）未感染。在 63 次传播中，62 次（98.4%）是在症状出现前 6 小时内追踪到的，而只有 1 次是在症状出现前 6-12 小时内发现的。确诊感染前24小时内，共追踪到与无症状感染者有过会面/接触的人员1557人。在这1557人中，仅发现1人感染，计算感染率为0.06%。统计发现，有症状患者的传播率明显高于无症状个体的传播率（P < 0.05）。在研究人群中，COVID-19的症状前和无症状传播风险较低，传播风险分别为1.12%和0.06%。在症状出现前超过 6 小时的接触中，症状前感染变得非常罕见。患者出现明显症状前约9小时即可追踪到感染传播，但发病率低至该时期总接触者的0.02%左右。