FIND evaluation of SARS-CoV-2 antigen (Ag) detecting tests

SARS-CoV-2 antigens are shed as the virus replicates during active infection, and thus their detection can be used to diagnose current infection.

FIND is conducting prospective diagnostic evaluation studies in collaboration with multiple, independent sites to determine the accuracy of COVID-19 antigen (Ag) detecting tests (RDTs). We are currently busy evaluating assays that have already been selected (Table 1) and the expression of interest (EOI) to participate in the Ag RDT evaluations is now closed.

Test submissions were selected through a scoring system taking into consideration:

• supplier-reported analytical performance
• supplier-reported clinical performance and size of the related study population/number of COVID-19 positive cases
• ease of use of the test (need for an instrument, sample type)
• manufacturing and distribution capacity (especially related to the ability of the company to access LMICs market)
• regulatory status – products with approval from stringent regulatory bodies such as FDA EUA or WHO EUL are scored higher than CE-IVD self-reported tests which are in turn scored higher than RUO tests.

Status of submission to WHO EUL or approval/failure of another COVID-19 test has also been considered for the final stage of selection.

Antigen RDT evaluation protocol summary

Results for ongoing evaluations will continue to be updated on a routine basis (Table 1). Last update: 03 January 2022

Note: Lower test sensitivity has been observed repeatedly in the evaluations performed in the study sites in India. A root-cause analysis exercise, which included sampling and testing parameters, has been conducted and did not return a conclusive cause for this lower performance compared to results obtained at other study sites. It must be noted that all the referenced evaluations were conducted prior to the emergence of the newly detected variants in India, such as B.1.617. A remaining hypothesis, which has not been confirmed, is that the higher temperature and humidity conditions observed in India may be contributing to varied performance.

More information

For questions relating to the evaluation of immunoassays, please contact our Emerging Threats team.