The Tokyo Metropolitan Government external quality assessment of SARS-CoV-2 nucleic acid amplification tests for clinics in 2023.

An external quality assessment (EQA) on nucleic acid amplification tests for SARS-CoV-2 was conducted among clinics that introduced testing instrument through the Tokyo Subsidy Program for Facilities and Equipment for Testing in COVID-19 in 2023. The survey samples consisted of sample 1 (20,000 copies/mL), sample 2 (10,000 copies/mL), and negative sample. Results were obtained through Cycle threshold (Ct) values as well as positive-negative result determinations. On-site technical support was provided to the 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 in this survey. The qualitative test results showed high correctness rates, 95.2% for sample 1, 93.2% for sample 2, and 96.3% for negative sample. Differences in Ct values were observed among reagents and instruments. Technical support were provided to 63 clinics. It revealed that discrepancies of qualitative test were mainly due to deviations from the protocol instructions, mixing 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.