Comparison of Fourteen Rapid Point-of-Care Antigen Tests for SARS-CoV-2: Use and Sensitivity

Abstract

Fast, sensitive techniques are advisable for SARS-CoV-2 detection. Various rapid SARS-CoV-2 antigen detection tests have been developed, but type and quality of the sample, stage of the disease and viral load can all have an impact on their sensitivity. For this study, a total of 486 swabs were processed and checked with various commercially available tests and then compared with q(RT)-PCR (the gold-standard method). Total sensitivity varied considerably; for example, 42.10% (nal von minden and Tody Laboratories), 68.42% (Cahnos) and 84.78% (PCL). Sensitivity reached 100% when the cycle threshold (Ct) was lower than 22 in almost all tests, although this dropped considerably when the Ct was higher above 30, where only 3 tests identified 40% or more positive samples and in 5 cases it was 0%. What is more, only 2 cases were 100% accurate when viral load was higher than 5 log/103 cells and accuracy was 0% in 12 cases when viral load was lower than 4 log/103 cells. These results, particularly taking into consideration the fact that they used normalized viral load, suggest that antigen detection tests have their role in the fast triage of positive patients, but that considerable care should be taken with negative results, which is even more important if they are used for massive screening.