Non-healthcare workers with a high potential for exposure to severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) may contribute to the virus spreading. Data among asymptomatic and high exposure risk populations is still scarce, in particular Chiang Mai and Lamphun provinces, Thailand. We conducted a cross-sectional observational study aiming to assess the prevalence of SARS-CoV-2 RNA positivity, anti-SARS-CoV-2 IgM/IgG, and potential associated factors among asymptomatic/mild symptomatic individuals with a high exposure risk in Chiang Mai and Lamphun provinces, during the second wave of outbreak in Thailand (November 2020–January 2021). Socio-demographic data was collected through an on-line questionnaire prior to collection of nasopharyngeal/throat swab samples and blood samples tested for SARS-CoV-2 RNA (DaAn Gene, China) and anti-SARS-CoV-2 IgM/IgG antibodies (commercial lateral flow immunoassays), respectively. Univariable and multivariable logistic regression analysis were used to analyze associated factors. None of 1,651 participants were found positive for SARS-CoV-2 RNA (0%, 95% confidence intervals, CI: 0–0.2). Fourteen were positive for anti-SARS-CoV-2 IgM/IgG antibodies (0.9%, 95% CI: 0.5–1.4), including 7 positives for IgM and 7 positives for IgG (0.4%, 95% CI: 0.2–0.9). Being over 50 years old was independently associated with virus exposure (OR: 5.8, 95% CI: 1.0–32.1%, p = 0.045). Despite high exposure risk, no current infection was found, and a very high proportion was still susceptible to SARS-CoV-2 infection and would clearly benefit from vaccination. Continuing active surveillance, rolling out of vaccination and monitoring response to vaccine will help better control the COVID-19 spread.
【초록키워드】 COVID-19, SARS-CoV-2, IgG, IgM, Vaccine, coronavirus, vaccination, antibody, cross-sectional, SARS-COV-2 infection, Infection, risk, virus, anti-SARS-CoV-2, observational study, Population, Spread, Prevalence, China, Asymptomatic, IgG antibodies, outbreak, IgM/IgG, Factors, Active surveillance, second wave, SARS-CoV-2 RNA, Lateral flow immunoassays, questionnaire, Analysis, exposure to, acute respiratory syndrome, Factor, Confidence intervals, 95% CI, acute respiratory syndrome coronavirus, Blood samples, multivariable logistic regression, demographic data, blood sample, help, participant, swab samples, Multivariable logistic regression analysis, positive, being, susceptible, benefit, swab sample, tested, proportion, conducted, was collected, were used, contribute, symptomatic individual, 【제목키워드】 anti-SARS-CoV-2, Population,