Laboratory diagnosis challenges of Covid-19: a Real-time RT-PCR assay-based survey

 A novel coronavirus has recently been discovered in Wuhan, China in December 2019 named SARS-COV-2. Sensitive molecular assays are now available for detection of SARS-COV-2. The aims of this study were to detect positive subjects of SARS-COV-2 and to survey some challenges that are encountered practically in detection of the virus by Real-time RT-PCR (rRT-PCR) technique.

 271 subjects including 105 women and 166 men were registered by census method from 15 April to 15 Jun of 2020. Nasopharyngeal and oropharyngeal swab samples of suspicious cases were collected for RNA extraction to identify SARS-COV-2 by rRT-PCR amplification.

 69% of the positive SARS-COV-2 patients over the age 50 were men. However, technically the results showed that in the time period of 15 April to 15 May of 2020 the contents of received rRT - PCR kits were infected with positive control.  8 % of certain negative control samples showed a signal resembling to that of the positive samples in the rRT - PCR process. In addition, the results showed that in some of the rRT - PCR kits the master mix would produce signals like positive control without adding the sample to it automatically in 7 % of the tests.

 Having different types of negative control for diagnosis of SARS-COV-2 is necessary to reduce the chance of having false positive results.