Clinical Validation of Standard Q COVID-19 Antigen and IgM/IgG Combo Kit Assay at a Tertiary Care Center in Northern India.

 Expansion of the testing capacities for severe acute respiratory syndrome-coronavirus-2 is an important issue in the face of ever-increasing case load. So, there is need of point-of-care diagnostic tests in the existing laboratory capacities for early treatment, isolation, and clinical decision making, especially in resource limited settings.  This prospective cohort study was conducted at Jai Prakash Narayan Apex Trauma Center, All India Institute of Medical Sciences, New Delhi. Nasopharyngeal samples and blood samples were collected for antigen and antibody testing. Rapid antigen test was performed as per the kit's instructions. The performance of the kit was compared with the gold standard reverse transcription polymerase chain reaction (RT-PCR) testing.  Eighty-eight out of 110 patients tested positive by RT-PCR for coronavirus disease 2019 in last 48 to 72 hours were included in the study. Overall, the sensitivity of combined antibody test was 52%, antigen test 26%, and combined sensitivity of both antigen and antibody was 72.7%, respectively.  The combo kit needs to be used with caution in low prevalence settings, where cases may be missed.