THE POTENTIAL LOSS OF SARS-COV-2 CASES THAT ARE DETECTED USING RAPID ANTIGEN TESTING: A STUDY MODEL IN COVID-19 OUT-PATIENT CLINIC

Abstract

Introduction: The needs of precise screening method is an important step to prevent and control COVID-19 transmission. RT-PCR is a gold standard, but challenging due to its complexity. The Rapid Diagnostic Test (RDT) Antigen is promising and now has been used for community screening and a tool for traveler’s health passport. Aim: to identify the potential loss of SARS-CoV-2 positive people as a transmission source. Methods: The good quality of RDT-Antigen that marketed in Indonesia was chosen as a model to predict the undetected cases of SARS-CoV-2. The sensitivity and specificity of the RDT-Antigen was classified as group of Ct value £25, > 25, and negative results; there were 30 samples for each group. Result: The best performance RDT-Ag among other, showed the specificity 100% (for RTPCR negative) and sensitivity for RT-PCR positive with Ct £25 and Ct>25 was 100% and 37% consecutively. This was used as a model to calculate the patients that were screened in outpatient clinic. There were 5928 people and 1814 were positive by RT-PCR, 235 (13%) with Ct £25 and 1579 (87%) with Ct>25. The detected cases if it was tested with RDT-Antigen showed 100% for Ct £25 and only 37% of people with Ct>25. Thus the potential loss of cases were zero for Ct £25 and 995 cases for Ct>25. This makes 16.8% loss cases of the total people tested, or 55% of the total positive cases that will potentially transmit to others. Conclusion: The use of RDT Antigen for screening tools has a potential loss of cases by 16.8% from the total screened or 55% for the RT-PCR positive tested. These loss cases will become a source of transmission of the virus to others. This data can be used by policy maker for considering RDT Antigen as a screening tool.