Full spectrum of COVID-19 severity still being depicted.

Chaolin Huang and colleagues first reported the clinical features of patients infected with severe acute respiratory syndrome corona virus 2 (SARS-CoV-2; previously known as 2019-nCoV), which emerged in Wuhan, China. Their study will contribute to the diagnosis and treatment of 2019 novel coronavirus disease (COVID-19). Meanwhile, the conclusions have caused a certain degree of social panic.

Huang and colleagues only included 59 suspected cases with fever and dry cough, and 41 patients were confirmed to be infected with SARS-CoV-2. They concluded that SARS-CoV-2 infection was associated with a high rate of admission to intensive care units (13 [32%] of 41 patients) and mortality (six [15%] of 41 patients); however, we believe these conclusions were inaccurate and misleading.

Case fatality ratio should not be confused with mortality rate. Case fatality rate is defined as the proportion of people who die of a certain disease; however, mortality rate usually reflects the death rate in an entire population. The case fatality rate is therefore approximately 15% in the study population, but this estimate is also inaccurate since case detection is highly biased towards the more severe cases in the early stages. In fact, a large number of mild and asymptomatic patients might not receive timely diagnosis or health care, which can conceal the real incidence and allow disease progression.

Patients with SARS-CoV-2 infection are presenting with a wide range of symptoms. Most patients seem to have mild disease, and about 20% appear to progress to severe disease, including pneumonia, respiratory failure, and, in some cases, even death. As of Feb 12, 2020, WHO reports that 45 171 people have been diagnosed with SARS-CoV-2 worldwide, and 44 730 of these cases are in China. Of the confirmed cases in China, 8204 (18%) cases were recorded as severe infections, and 1114 (2%) patients died, which is a lower case fatality rate than previously reported.4, 5 The case fatality rate for COVID-19 reported by Huang and colleagues could be misunderstood, and detection bias should not be neglected.