Seroprevalence of hospital staff in a province with zero COVID-19 cases

• Published in: PloS one Vol. 16; no. 4; p. e0238088
• Main Authors: Nopsopon, Tanawin, Pongpirul, Krit, Chotirosniramit, Korn, Jakaew, Wutichai, Kaewwijit, Chuenkhwan, Kanchana, Sawan, Hiransuthikul, Narin
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.04.2021; Public Library of Science (PLoS)
• Subjects: Adult; Antibodies; Antibodies, Viral - blood; Asymptomatic; Biology and Life Sciences; Coronaviruses; COVID-19; COVID-19 - epidemiology; Disease transmission; Editing; Female; Health aspects; Health care; Hospitals; Humans; Immunoglobulin G; Immunoglobulin G - blood; Immunoglobulin M; Immunoglobulin M - blood; Immunoglobulins; Male; Medical personnel; Medicine; Medicine and Health Sciences; Middle Aged; People and Places; Personnel, Hospital - statistics & numerical data; Polymerase chain reaction; Public health; Research and Analysis Methods; Seroepidemiologic Studies; Serology; Severe acute respiratory syndrome coronavirus 2; Statistics; Systematic review; Thailand - epidemiology; Visualization; Thailand; Southeast Asia; Asia; Europe; China; Africa; North America; Bangkok Thailand
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0238088

COVID-19 seroprevalence data, particularly in less developed countries with a relatively low incidence, has been scant. We aimed to explore the seroprevalence of hospital staff in the area with zero confirmed COVID-19 case to shed light on the situation of COVID-19 infection in zero or low infection rate countries where mass screening was not readily available. A locally developed rapid immunoglobulin M (IgM)/immunoglobulin G (IgG) test kit was used for hospital staff screening of Ranong hospital which is located in a province with zero COVID-19 prevalence in Thailand from 17th April to 17th May 2020. All staff was tested, 100 of which were randomly invited to have a repeating antibody test in one month. (Thai Clinical Trials Registry: TCTR20200426002). Of 844 hospital staff, 82 were tested twice one month apart (response rate for repeating antibody test 82%). Overall, 0.8% of the participants (7 of 844) had positive IgM, none had positive IgG. Female staff had 1.0% positive IgM (95% CI: 0.5-2.1%) while male had 0.5% positive IgM (95% CI: 0.1-2.6%). No participants with a history of travel to the high-risk area or close contact with PCR-confirmed COVID-19 case developed SARS-CoV-2 antibodies. Among 844 staff, 811 had no symptoms and six of them developed IgM seropositive (0.7%) while 33 had minor symptoms and only one of them developed IgM seropositive (3.0%). No association between SARS-CoV-2 IgM status and gender, history of travel to a high-risk area, close contact with PCR-confirmed or suspected COVID-19 case, presence of symptoms within 14 days, or previous PCR status was found. None of the hospital staff developed SARS-CoV-2 IgG. COVID-19 antibody test could detect a considerable number of hospital staff who could be potential silent spreaders in a province with zero COVID-19 cases. Accurate antibody testing is a valuable screening tool, particularly in asymptomatic healthcare workers. Trial registration: This study was approved by the Institutional Review Board of Chulalongkorn University (IRB No.236/63) and the Institutional Review Board of Ranong Hospital. (Thai Clinical Trials Registry: TCTR20200426002).