Aims:
Numerous test kits of the detection of SARS-CoV-2 antibodies were released throughout 2020. Most international regulators allowed their use under Emergency Use Listing, which required limited performance evaluations. NRL and WHO undertook a comprehensive, head-to-head evaluation of the performance of SARS-CoV-2 test kits suitable for use in low- and middle-income countries.
Methods:
Well-characterised samples in sufficient volume to test many test kits were collected, randomised and aliquoted into panels. Test kits were tested for SARS-CoV-2 RNA positivity (n=199), specificity (n=300), analytical sensitivity, precision, lot-to-lot variation, seroconversion panels and potential cross-reactivity (n=55) and interference (n=35). Additional 31 samples from individuals previously infected with SARS-CoV-1 (n=18), MERS (n=4) and seasonal coronavirus (n=9) were tested. A total of 26 lateral flow devices (RDT) and nine EIAs were included in the study.
Results:
The concordance to RNA positivity for RDTs testing for IgG and IgM ranged from 77.4 to 100% and 55.8 to 99.5% respectively, whereas the EIA reported concordance ranging from 60.1 to 100%. Specificity of RDT IgG and IgM ranged from 81.0 to 99.0% and 34.3 to 99.0% and EIAs reported specificities of 74.0 to 100%. Cross reactivity and interference were detected in most assays with some having an unacceptable percentage of false reactions. Most assays cross-reacted with SARS-CoV-1 positive samples. Precision of EIA ranged from 3.7 to 15.5 % coefficient of variation.
Conclusions:
This study demonstrates a wide range of performance characteristic of SARS-CoV-2 assays and highlights the need for comprehensive, comparative testing of assay performance in an emergency setting.