External Quality Assessment of MERS-CoV Molecular Diagnostics During the 2015 Korean Outbreak

Seong, Moon-Woo; Lee, Seung Jun; Cho, Sung Im; Ko, Kyungphil; Kim, Mi-Na; Sung, Heungsub; Kim, Jae-Seok; Ahn, Ji Soo; Yu, Byung Su; Kim, Taek Soo; Kim, Eui Chong; Park, Sung Sup

Recently, an international EQA of molecular diagnostics for MERS-CoV was conducted across 106 laboratories from six continents; this is the only published report on EQA of MERS-CoV testing [8] . To the best of our knowledge, this study is the first EQA of MERS-CoV testing conducted in an affected region during an outbreak worldwide. The Korean outbreak of 2015 was the largest outbreak of MERS-CoV infection outside Middle East Asia, which demanded a rapid expansion of MERS-CoV testing laboratories. Unapproved commercial kits for in vitro diagnostic use were introduced to clinical laboratories without formal validation as a diagnostic test, which raised an issue of their quality. In this study, more than 46 laboratories participated in EQA over two phases and showed overall good results. Nevertheless, our EQA scheme has some limitations. First, this scheme could not reflect important practical steps, such as sample preparation or nucleic acid extraction, because both in vitro transcribed RNA and extracted RNA were used for EQA. Second, for the first phase, the analytical validation was set by using the participants' own dilution scheme and there was no limitation on repeating the tests to obtain the final results. Therefore, not all laboratories provided results for all of the concentrations analyzed in this study, and some positive results for the lower concentrations could be from various test repeats. This means that the results from this EQA phase may be not suitable for inter-laboratory comparison. Third, the second phase assessment comprised only three samples, including one each of strong positive and weak positive, but did not include diverse concentrations especially on the lower end of the analytical sensitivity of rRT-PCR. Lastly, other coronaviruses, such as HCoV-NL63 or HCoV-229E, were not included in the assessment of the analytical specificity of the diagnostic assays.