Comparison of four commercial RT‐PCR diagnostic kits for COVID‐19 in China

We compared the sensitivity and specificity of four commercial coronavirus disease (COVID‐19) diagnostic kits using real‐time reverse transcription–polymerase chain reaction (RT‐PCR). Kits I‐IV approved by the State Drug Administration of China were selected, and the detection targets were ORF1ab gene and N gene. Specificity was evaluated by detecting other respiratory viruses. The sensitivity and batch effect of each kit were evaluated by testing 10‐fold dilutions of RNA. Clinical application was verified by testing nasopharyngeal swab and sputum specimens from COVID‐19 patients. Among the 78 cases infected by other respiratory viruses, no amplification curve was observed using these four COVID‐19 RT‐PCR kits. The minimum detection limits of kits I‐IV were 10(−6), 10(−5), 10(−5), and 10(−6) dilutions, respectively, and concentrations were 10 copies/mL (10(−5) dilution) and 1 copies/mL (10(−6) dilution). The sensitivities of kits I‐IV detected using 142 nasopharyngeal swab specimens from COVID‐19 patients were 91.55%, 81.69%, 80.28%, and 90.85%, respectively, while they were 92.68%, 85.37%, 82.93%, and 93.90%, respectively, for the 82 sputum samples. The specificity of each kit was 100.00% (77/77). The total expected detection rate using sputum samples was 88.59% (691/780) higher than 86.15% (672/780) of nasopharyngeal swabs. Comparison of nasopharyngeal swab and sputum samples from the same COVID‐19 patient led to the detection of ORF1ab and N genes in 16 (100%) sputum samples; only ORF1ab and N genes were detected in 12 (75%) and 14 (87.5%) nasopharyngeal swab specimens, respectively. In conclusion, comparison of commercial COVID‐19 RT‐PCR kits should be performed before using a new batch of such kits in routine diagnostics.