Center of Scientific Excellence for Influenza Viruses, National Research Centre, Giza, Egypt.
Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America.
PLoS Pathog. 2021 Mar 11;17(3):e1009413. doi: 10.1371/journal.ppat.1009413. eCollection 2021 Mar.
SARS-CoV-2 virus is transmitted in closed settings to people in contact with COVID-19 patients such as healthcare workers and household contacts. However, household person-to-person transmission studies are limited. Households participating in an ongoing cohort study of influenza incidence and prevalence in rural Egypt were followed. Baseline enrollment was done from August 2015 to March 2017. The study protocol was amended in April 2020 to allow COVID-19 incidence and seroprevalence studies. A total of 290 households including 1598 participants were enrolled and followed from April to October 2020 in four study sites. When a participant showed respiratory illness symptoms, a serum sample and a nasal and an oropharyngeal swab were obtained. Swabs were tested by RT-PCR for SARS-CoV-2 infection. If positive, the subject was followed and swabs collected on days three, six, nine, and 14 after the first swab day and a serum sample obtained on day 14. All subjects residing with the index case were swabbed following the same sampling schedule. Sera were collected from cohort participants in October 2020 to assess seroprevalence. Swabs were tested by RT-PCR. Sera were tested by Microneutralization Assay to measure the neutralizing antibody titer. Incidence of COVID-19, household secondary attack rate, and seroprevalence in the cohort were determined. The incidence of COVID-19 was 6.9% and the household secondary attack rate was 89.8%. Transmission within households occurred within two-days of confirming the index case. Infections were asymptomatic or mild with symptoms resolving within 10 days. The majority developed a neutralizing antibody titer by day 14 post onset. The overall seroprevalence among cohort participants was 34.8%. These results suggest that within-household transmission is high in Egypt. Asymptomatic or mild illness is common. Most infections seroconvert and have a durable neutralizing antibody titer.
SARS-CoV-2 病毒在封闭环境中传播，接触 COVID-19 患者（如医护人员和家庭接触者）的人会被感染。然而，家庭人际传播的研究有限。正在进行一项关于埃及农村流感发病率和流行率的队列研究的家庭参与了该研究。基线登记从 2015 年 8 月至 2017 年 3 月进行。2020 年 4 月，研究方案进行了修订，以允许进行 COVID-19 发病率和血清阳性率研究。在四个研究地点，共招募了 290 户家庭，包括 1598 名参与者，并在 2020 年 4 月至 10 月进行了随访。当参与者出现呼吸道疾病症状时，采集血清样本和鼻拭子及咽拭子。用 RT-PCR 检测 SARS-CoV-2 感染。如果为阳性，对该受试者进行随访，并在第一次拭子日的第 3、6、9 和 14 天以及第 14 天采集血清样本。所有与指数病例同住的人都按照相同的采样方案进行拭子采样。2020 年 10 月从队列参与者中采集血清样本，以评估血清阳性率。用 RT-PCR 检测拭子。用微量中和试验检测血清，以测量中和抗体滴度。确定队列中的 COVID-19 发病率、家庭二次攻击率和血清阳性率。COVID-19 的发病率为 6.9%，家庭二次攻击率为 89.8%。在确认指数病例后两天内，家庭内发生了传播。感染为无症状或轻症，症状在 10 天内消退。大多数人在发病后第 14 天产生中和抗体滴度。队列参与者的总体血清阳性率为 34.8%。这些结果表明，埃及的家庭内传播率较高。无症状或轻症很常见。大多数感染病例会发生血清学转换，产生持久的中和抗体滴度。
