The above comments are from the background section of the March 18 WHO update on nCoV surveillance. As seen above, the vast majority of the confirmed cases have been severe, and 9 of the 13 outcomes have been fatal (two of the confirmed cases remain hospitalized). As noted above, one of the confirmed cases was mild and did not require hospitalization or treatment, which is also true for one of the probable cases. However, it is the mild cases in the confirmed clusters that have raised concerns, and the failure to confirm nCoV in symptomatic contacts has force WHO to qualify their description of such cases as “seemingly sporadic”.
Clusters provide considerable insight into what is and isn’t been detected and the large number of symptomatic contacts which test negative in PCR tests raises concerns that the nCoV levels in upper respiratory samples in mild cases is undetectable.