1. Sensitivity and specificity: clinical validation study of the SARS-CoV-2 Ab Rapid Test was conducted in 2020 in Shenzhen, China. 137 specimens from confirmed COVID-19 patients and 209 specimens from healthy individuals were tested. The kit demonstrated the sensitivity of 95.6% (131/137) and the specificity of 95.2% (199/209).
2. Samples were collected from COVID-19 confirmed cases with clinical symptoms, laboratory abnormalities or pulmonary imaging manifestations. No tests have been performed on specimens from latent infections or patients in the incubation period. It was observed that the detection rate of the kit was closely related to the time of disease onset, the kit showed higher positive detection rate in specimens from patients with delayed onset. Therefore, the interpretation of the test results should consider the specimen's collection time.
Clinical importance of combined RNA and antibody testing
COVID-19 serological markers dynamics (Total Ab/ IgM/ IgG):
20%-40% of the patients developed antibodies on days 0-7 after onset
60%~70% of the patients developed antibodies on days 8-11 after onset
> 90% of the patients had detectable levels of antibodies starting from day 12 after onset.
COVID-19 molecular markers dynamics (RNA):
RNA was detected in 60-75% of the patients on days 0-8 after onset RNA levels decrease to 40-50% starting from day 9 after onset
COVID-19 combined serological and molecular markers increases the sensitivity of diagnosis while maintaining the high specificity. Among the serological markers, total Ab detection has greater significance in clinical practice.