Editor’s Note: This is an excerpt of an editorial, co-written by Anthony Fauci, director, National Institute of Allergy and Infectious Diseases, and other experts, that appears in the current edition of the New England Journal of Medicine.
A degree of clarity is emerging from this report, (“Early transmission dynamics in Wuhan, China,” Li Q. Guan X and colleagues, New England Journal of Medicine, Jan. 29.)
The median age of the patients was 59 years, with higher morbidity and mortality among the elderly and among those with coexisting conditions (similar to the situation with influenza); 56 percent of the patients were male. Of note, there were no cases in children younger than 15 years of age.
Either children are less likely to become infected, which would have important epidemiologic implications, or their symptoms were so mild that their infection escaped detection, which has implications for the size of the denominator of total community infections.
On the basis of a case definition requiring a diagnosis of pneumonia, the currently reported case fatality rate is about 2 percent.
In another article in The Journal, Guan et al. report mortality of 1.4 percent among 1,099 patients with laboratory-confirmed Covid-19; these patients had a wide spectrum of disease severity.
If one assumes that the number of asymptomatic or minimally symptomatic cases is several times as high as the number of reported cases, the case fatality rate may be considerably less than 1 percent.
This suggests that the overall clinical consequences of Covid-19 may ultimately be more akin to
those of a severe seasonal influenza (which has a case fatality rate of approximately 0.1 percent) or a pandemic influenza (similar to those in 1957 and 1968) rather than a disease similar to SARS or MERS, which have had case fatality rates of 9 to 10 percent and 36 percent, respectively.