The Tokyo Metropolitan Government External Quality Assessment of SARS-CoV-2 Nucleic Acid Amplification Tests for...

In 2023, an external quality assessment (EQA) of nucleic acid amplification tests for SARS-CoV-2 was conducted among clinics that implemented testing instruments through the Tokyo Subsidy Program for Facilities and Equipment for Testing in COVID-19. The survey samples consisted of sample 1 (20,000 copies/mL), sample 2 (10,000 copies/mL), and a negative sample. Results were obtained through cycle threshold (Ct) values and positive-negative result determinations. On-site technical support was provided to clinics that responded incorrectly. A total of 544 clinics (589 instruments) participated, and Abbott's ID NOW ^TM (82.2%) was the most widely used instrument. The qualitative test results showed high accuracy rates of 95.2% for Sample 1, 93.2% for Sample 2, and 96.3% for negative samples. Differences in Ct values were observed between reagents and instruments. Technical support was provided to 63 clinics. The discrepancies in the qualitative tests were mainly due to deviations from the protocol instructions, mixing of all three survey samples into one vial, and errors caused by foaming. This survey was unique in that the participants were mostly end users who were not laboratory testing specialists and mainly used point-of-care testing instruments. It is important to continue EQA to improve and maintain testing accuracy.