Clinical performance and potential of a SARS-CoV-2 detection kit without RNA purification steps

Sato, Y.; Kondo, T.; Moriai, M.; Nirasawa, S.; Saeki, M.; Yakuwa, Y.; Katayama, Y.; Kitayama, I.; Kobayashi, R.; Endoh, A.; Asanuma, K.; Fujiya, Y.; Takahashi, S.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is rapidly spreading globally. Early diagnosis plays an essential role in controlling the infection. Therefore, early and accurate SARS-CoV-2 detection assays along with easy operation are required. The aim of this study was to compare the clinical performance of the Ampdirect™ 2019-nCoV Detection Kit (SHIMADZU assay), which does not require RNA purification steps, with that of the preexisting SARS-CoV-2 detection assays, which use a purified RNA template. A total of 71 samples (65 nasopharyngeal specimens and 6 sputum specimens) were collected from 32 individuals, including patients infected with SARS-CoV-2 and those with suspected infection. The sensitivity and kappa (κ) coefficient were assessed between the SARS-CoV-2 detection assays using the reference standard, which was defined as a true positive result by any one of the four SARS-CoV-2 detection assays. The overall sensitivity and κ coefficient of the SHIMADZU assay were 86.0% (95% confidence interval [CI]: 77.9-94.2) and 0.83 (95% CI: 0.69-0.96), respectively. In particular, among the 18 samples collected within 10 days from symptom onset, the sensitivity and κ coefficient of the SHIMADZU assay were 100% and 1.0, respectively. Although a relatively small number of samples was evaluated, the SHIMADZU assay showed good analytical performance and as such would be highly useful for the detection of SARS-CoV-2. The test can be performed easily and quickly and has the potential for future applications in situations where a highly sensitive diagnosis is required. © 2021