ABSTRACT
Background: Contact tracing with quarantine of SARS-CoV-2 positive contacts is required on an unprecedented scale worldwide.Methods: During February 1-March 25, 2020, COVID-19 cases in Hubei province were traced by more than 1800 teams. PCR positive contacts without COVID-19 symptoms with two or more consecutive positive tests for SARS-CoV-2 were categorized as: (a) asymptomatic SARS-CoV-2 if without COVID-19 symptoms throughout the > 14 days of quarantine, (b) pre-symptomatic SARS-CoV-2 if COVID-19 symptoms started during the quarantine, and (c) false positive contacts if two consecutive follow-up qRT-PCRs were negative after an initial positive SARS-CoV-2 test.Findings: 48,944 COVID-19 patients identified 277,066 contacts who were tested for SARS-CoV-2; upon ascertainment, 3,152 contacts without symptoms were SARS-CoV-2 PCR positive without symptoms, and 50 contacts were false positives. After quarantine, 2928 were classified as asymptomatic and 174 were pre-symptomatic SARS-CoV-2 contacts, with a pre-symptomatic case fatality (11/174) of 6.3%. The average interval between the initial SARS-CoV-2 PCR positive and onset of COVID-19 symptoms was 9.7 days, and the average time from onset of symptoms to death for deceased pre-symptomatic cases was 6.3 days (range = 1 - 35 days).Interpretation: Contact tracing of COVID-19 cases required many contact tracing teams, testing all contacts without COVID-19 symptoms, and quarantine of asymptomatic SARS-CoV-2 positive contacts. Countries with limited contact tracing, testing and quarantine of asymptomatic SARS-CoV-2 infected contacts under-estimate the number of infected asymptomatic SARS-CoV-2 contacts, and their contribution to COVID-19 spread.Funding Statement: National Natural Science Foundation of China (82041021), Bill & Melinda Gates Foundation (INV-006371).Declaration of Interests: The authors declare they have no conflict of interest.Ethics Approval Statement: This study was approved by the Medical Research Ethics Review Committee of Sun Yat-sen University School of Public Health (No.: 2020016). Consistent with public health regulations the informed consent was waived because data were collected as part of public health practice associated with the COVID-19 outbreak investigation and response.
Subject(s)
COVID-19ABSTRACT
Importance A large number of healthcare workers (HCWs) were infected by SARS-CoV-2 during the ongoing outbreak of COVID-19 in Wuhan, China. Hospitals are significant epicenters for the human-to-human transmission of the SARS-CoV-2 for HCWs, patients, and visitors. No data has been reported on the details of hospital environmental contamination status in the epicenter of Wuhan. Objective To investigate the extent to which SARS-CoV-2 contaminates healthcare settings, including to identify function zones of the hospital with the highest contamination levels and to identify the most contaminated objects, and personal protection equipment (PPE) in Wuhan, China. Design A field investigation was conducted to collect the surface swabs in various environments in the hospital and a laboratory experiment was conducted to examine the presence of the SARS-CoV-2 RNA. Setting Six hundred twenty-six surface samples were collected within the Zhongnan Medical Center in Wuhan, China in the mist of the COVID-19 outbreak between February 7 - February 27, 2020. Participants Dacron swabs were aseptically collected from the surfaces of 13 hospital function zones, five major objects, and three major personal protection equipment (PPE). The SARS-CoV-2 RNAs were detected by reverse transcription-PCR (RT-PCR). Main Outcomes and Measures SARS-CoV-2 RNAs Results The most contaminated zones were the intensive care unit specialized for taking care of novel coronavirus pneumonia (NCP) (31.9%), Obstetric Isolation Ward specialized for pregnant women with NCP (28.1%), and Isolation Ward for NCP (19.6%). We classified the 13 zones into four contamination levels. The most contaminated objects are self-service printers (20.0%), desktop/keyboard (16.8%), and doorknob (16.0%). Both hand sanitizer dispensers (20.3%) and gloves (15.4%) were most contaminated PPE. Conclusions and Relevance Many surfaces were contaminated with SARS-CoV-2 across the hospital in various patient care areas, commonly used objects, medical equipment, and PPE. The 13 hospital function zones were classified into four contamination levels. These findings emphasize the urgent need to ensure adequate environmental cleaning, strengthen infection prevention training, and improve infection prevention precautions among HCWs during the outbreak of COVID-19. The findings may have important implications for modifying and developing urgently needed policy to better protect healthcare workers during this ongoing pandemic of SARS-CoV-2.