via @goldencaskcap

An Apple Daily article dated Feb 10th argued that China’s CDC was seeking to downplay the number of confirmed coronavirus pneumonia cases by revising the criteria used for designating ‘confirmed’ cases to exclude patients with no symptoms from the tally, seemingly against WHO guidelines.

The claim was based on a reading of the fourth edition of China’s official treatment guidelines and an article from February 9th reporting that Heilongjiang province had excluded 13 cases of asymptomatic patients who tested positive for coronavirus from confirmed cases because they were asymptomatic.

To understand if the story is correct, we need examine several points one by one:

Do China’s Definitions Contradict the WHO Guidelines?

The WHO guidelines define “confirmed cases” as “[a] person with laboratory confirmation of 2019-nCoV infection, irrespective of clinical signs and symptoms”, which is why China’s exclusion of asymptomatic cases was viewed as problematic.

The guidelines also considers ‘suspect cases’ including several types of patient with respiratory tract symptoms and a history of contact with China or the virus. Another group, ‘Probable cases”, are in turn defined as “a suspect case for whom testing for 2019-nCoV is inconclusive or is tested positive using a pan-coronavirus assay and without laboratory evidence of other respiratory pathogens.”

If you read carefully, you’ll notice that two different diagnostic assays are mentioned in the definition of probable cases: one specifically for 2019- nCoV and the other for pan-coronavirus which includes testing for other varieties of coronaviruses.The WHO guidelines address asymptomatic patients testing positive for 2019-nCoV, but because probable cases are all suspect cases and thus show symptoms, the WHO guidelines do not address specifically address asymptomatic carriers that are tested positive on assays other than the 2019-nCoV PCR.

China’s 4th Edition guidelines defines confirmed cases as clinically diagnosed cases or suspected cases with either a positive covid19 rt-PCR test or gene sequencing.

（三）确诊病例。 临床诊断病例或疑似病例，具备以下病原学证据之一者： 1.呼吸道标本或血液标本实时荧光 RT-PCR 检测新型冠状病 毒核酸阳性； 2.呼吸道标本或血液标本病毒基因测序，与已知的新型冠状 病毒高度同源。