Adjusted age-specific case fatality ratio during the COVID-19 epidemic in Hubei, China, January and February 2020

Julien Riou; Anthony Hauser; Michel J Counotte; Christian L Althaus

The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has resulted in more than 260,000 confirmed cases and 11,000 deaths, as of 20th March 2020 [1] . The infection emerged in late 2019 as a cluster of cases of pneumonia of unknown origin in Wuhan, Hubei province, China and was named coronavirus disease 2019 in January 2020 [2, 3] . The largest outbreak to date is still that in China, but the number of reported deaths from Covid-19 in Italy (4,032 deaths, population 60 million) has overtaken China (3,261 deaths, population 1.4 billion) [1] . The epidemic appears to have originated from multiple zoonotic transmission events of a coronavirus, with the animal source remaining unknown [4] . The causal agent, SARS-CoV-2, was identified in January 2020 [5, 6] . The transmission characteristics of SARS-CoV-2 appear to be similar to those of the 1918 pandemic influenza strain [7] , but, at this early stage, its mortality rate is still unknown. During the early phase of A PREPRINT -22 MARCH 2020 the pandemic, reliable estimates of overall mortality, i.e. the proportion of all people with SARS-CoV-2 infection who will die from the disease are needed to plan health care capacity and for epidemic forecasting. Clinicians need to know age-and sex-specific mortality among symptomatic patients seeking care to assess prognosis and, in severe situations, prioritize patients with the best expected outcomes.