Patients without travel history were likely to have an antibody for SARS-CoV-2 (13.9% vs 3.2%) and patients without close contact to the case also had more chance to develop an antibody (12.3% vs 9.1%). a locally developed rapid IgM/IgG test kit Results Overall, 5.5% of the participants (47 of 857) had positive IgM, 0.2% (2 of IRL-2500 857) had positive IgG which both of them also had positive 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%). Conclusions COVID-19 antibody test could detect a substantial number of potential silent spreaders in Thai community hospitals where the nasopharyngeal PCR was not readily available, and the antigen test was prohibited. Antibody testing should be encouraged for mass screening in a limited resource setting, especially in asymptomatic individuals. Trial registration TCTR20200426002. strong class=”kwd-title” Keywords: COVID-19, SARS-CoV-2, seroepidemiologic studies, hospitals, Thailand Strengths and limitations of this study This study covered all regions in Thailand and consisted of community hospitals from 35 out of 77 provinces. We used a locally developed IgM/IgG test kit with high internal validation to shed light on the actual COVID-19 situation in areas in which nasopharyngeal PCR testing was not readily available. This study provided Rabbit polyclonal to IQCD a real-life experience to gather crucial information despite restricted resources. We did not have a chance to perform the serological test among the COVID-19 confirmed cases as the mild case had to get quarantined and the moderate and severe ones were referred to a higher level of care, which could affect the seroprevalence. We could not perform multiple serological tests at different time points as doing so was not approved by the ethics committee. Introduction PCR was introduced as a diagnostic test of choice for COVID-19 infection. However, it might not be readily available or affordable in many facilities and could pose an unnecessary risk to the healthcare providers during the specimen collection. Besides, a recent study raised a concern of false-negative results from the nasopharyngeal PCR test for SARS-CoV-2 in patients with high pretest probability and encouraged the development of a highly sensitive test.1 Antibody testing provides additional information for epidemic investigation and control with high sensitivity and simplicity, especially when used along with the nasopharyngeal PCR test. At an early stage of the COVID-19 pandemic, antibody testing was used for mass screening to identify and track the missing silent spreaders in Singapore.2 Asymptomatic patients are considered to be one of the important sources of COVID-19 transmission,3 with approximately one-fifth transmission rate to close contact individuals.4 Additionally, there was a 13% estimated proportion of asymptomatic patients IRL-2500 with COVID-19 in general and 37% in healthcare providers.5 While the nasopharyngeal PCR test was considered gold-standard, there were increasing studies that reported both PCR and antibody test results. In the early phase of pandemic, there was a study in China reported a 2.5% overall COVID-19 seroprevalence in the hospital setting with subgroup analysis of 1 1.8% in healthcare workers and 3.5% in asymptomatic patients.6 Recent meta-analysis reported 8% SARS-CoV-2 seroprevalence in healthcare workers before vaccine initiation.7 An IRL-2500 early study on the development of SARS-CoV-2 antibodies in symptomatic patients with COVID-19 reported that IgM had the highest value during 20C22?days after onset while IgG had the highest value during 17C19?days after onset.8 More complete information on immunoglobulin development was reported in a recent systematic review that IgM had median seroconversion time between four to 14 days, reached its peak at 2C5?weeks, then declined to an undetectable level at 6?weeks postonset while IgG had median seroconversion time between 12 and 15?days, reached its peak at 3C7?weeks, then diminished after 8?weeks after onset.9 Since SARS-CoV-2 infectivity was likely to diminish after 8C13 days postonset,10 antibody tests for IgM seroprevalence might not suit for early diagnosis of. IRL-2500
Patients without travel history were likely to have an antibody for SARS-CoV-2 (13