COVID-19: What is the Denominator

Since the 1st cases of infection by SARS-CoV-2 were reported in China, we have all been confronted by death and case-fatality statistics, which are both misleading and inaccurate. As of this morning, 2837 from a total of 83 774 reported cases of COVID-19 were fatal. Public Health professionals, the lay public, and politicians will conclude that this disease carries a “mortality rate” of 3.4%. Relatively few realize that “only” 1.4% of patients treated outside of Mainland China have died of COVID-19: 0.7% of passengers on the Diamond Princess cruise ship, 0.5% of patients in South Korea, etc. One explanation for these discrepant case-fatality statistics is related to demography. Patients reported by official sources have a higher mean age and prevalence of underlying chronic disease than the general Chinese population (or international travelers). Case-definition, variation in quality of care, genetic and nutritional factors might also explain higher fatality rates among Chinese patients. Indeed, several of the patients who died of COVID-19 outside of Mainland China have also been Chinese Nationals. A fundamental error in all of this could be related to the term, “reported cases.” How many infections in China are asymptomatic or sub-clinical? If, for example, only one-in-10 individuals who acquire infection by SARS-CoV-2 are sufficiently ill to visit a clinic or hospital, the true case-fatality rate decreases from 3.4% to 0.34% A seroprevale...
Source: GIDEON blog - Category: Databases & Libraries Authors: Tags: Epidemiology ProMED Source Type: blogs