The fatality rate of the new coronavirus remains one of the big unknowns of this pandemic.
This is due to the fact that SARS-CoV-2 infection causes a wide range of symptom severity: from lack of symptoms to mild and severe disease, pneumonia, and death.
However, analysis of all 72,342 cases diagnosed in China as of February 11, shows for 81 per cent of patients the disease starts mildly, 14 per cent develop severe symptoms, and around 4-5% per cent are critical.
More recent data, pooled from 14 European countries, indicate that only about 40 per cent confirmed cases are hospitalized, with two per cent of these requiring critical care.
The great majority of deaths occur in people over 65 years of age or with an underlying chronic condition or disease.
Major risk factors for severe illness and death include hypertension, diabetes, cardiovascular disease and obesity.
Men are more vulnerable to disease then women. In contrast, children are considerably less susceptible to developing the disease, although they do seem to get infected. Their role in spreading the virus remains to be determined.
Initial data suggested a case fatality rate (CFR) of around two per cent (which means 2 deaths out of every 100 confirmed cases), but those first estimates did not include asymptomatic or undiagnosed cases.
A more recent study estimates that the adjusted case fatality rate in China was 1.4 per cent for confirmed cases and 0.66 per cent when considering infected but undiagnosed cases.
Another study based on data from Italy estimates that the lethality rate in Lombardy was of 0.84 for every 100 infected cases.
First results in Spain: The first results of the national seroprevalence study indicate that, between January and beginning of May, around 5 per cent of the country’s population was infected by the virus. This means that the infection fatality rate in Spain was around one (one death for every 100 infected people).
As the pandemic advances, it is clear that the reported fatality rate varies between countries (roughly, between 1 and 10 per cent of confirmed cases), and that this depends on the number of diagnosed individuals and other factors such as the percentage of vulnerable people (elderly or with chronic conditions) and the capacity of health systems.
In any case, the case fatality rate of COVID-19 is lower than that of SARS (10 per cent) and could be up to ten times higher than that of seasonal flu (below 0.1 per cent).