External quality assessment for the molecular detection of MERS-CoV in China

Background: In May 2015, an imported case of Middle East respiratory syndrome coronavirus (MERS-CoV) infection occurred in China, so rapid and reliable diagnosis of suspected cases was necessary.

Objectives: An external quality assessment (EQA) program for the molecular detection of MERS-CoV was organized by the National Center for Clinical Laboratories (NCCL).

Study design: MS2 virus-like particles (VLPs) encapsulating specific RNA sequences of MERS-CoV were prepared as positive specimens. The assessment panel, which comprised of three negative and seven positive samples with different concentrations of VLPs, was distributed to 56 laboratories from 16 provinces, municipalities, or autonomous regions for molecular detection.

Results: Among the received data sets, three employed an in-house-developed real-time reverse-transcription polymerase chain reaction (rRT-PCR) assay and the others applied various commercial rRT-PCR kits. Overall, the majority of laboratories (46/56, 82.1%) could achieve 100% accuracy for MERS-CoV detection, but three laboratories (5.4%) still had room for improvement. Consequently, all negative samples were identified correctly, reaching 100% specificity. The false-negative rate was 3.1%, and most of the false-negative results were obtained from samples with relatively low concentration, indicating an urgent need to improve detection in weak-positive specimens.

Conclusions: The majority of participants possessed reliable diagnostic capacity for the detection of MERS-CoV. Moreover, EQA is indispensable because it can help enhance the diagnostic capability for the surveillance of MERS-CoV infections and allow comparison of the results among different laboratories.