Anawin Nopsopon, Krit Pongpirul, Korn Chotirosniramit, Narin Hiransuthikul
COVID-19 seroprevalence data has been scarce, especially in less developed countries with a relatively low infection rate.
Methods: A locally developed rapid IgM/IgG test kit was used for screening hospital staff and patients who required procedural treatment or surgery in 52 hospitals in Thailand from April 8 to June 26, 2020. A total of 857 participants were tested–675 were hospital staff and 182 were pre-procedural patients. (Thai Clinical Trials Registry: TCTR20200426002)
Overall, 5.5% of the participants (47 of 857) had positive immunoglobulin M (IgM), 0.2% (2 of 857) had positive immunoglobulin G (IgG) and IgM. Hospitals located in the Central part of Thailand had the highest IgM seroprevalence (11.9%). Preprocedural patients had a higher rate of positive IgM than the hospital staff (12.1% vs. 3.7%). Participants with present upper respiratory tract symptoms had a higher rate of positive IgM than those without (9.6% vs. 4.5%). Three quarters (80.5%, 690 of 857) of the participants were asymptomatic, of which, 31 had positive IgM (4.5%) which consisted of 20 of 566 healthcare workers (3.5%) and 11 of 124 preprocedural patients (8.9%).
COVID-19 antibody test could detect a substantial number of potential silent spreaders in Thai community hospitals. Antibody testing should be encouraged for mass screening, especially in asymptomatic individuals.