A novel cohort analysis approach to determining the case fatality rate of COVID-19 and other infectious diseases

Charit S Narayanan

The Coronavirus Disease 2019, or COVID-19, is a new virus that causes respiratory 2 ailments [1] . Its origins can most likely be traced back to Wuhan, China, where it was 3 first reported in December of 2019. It is comparable to other zoonotic coronaviruses 4 such as SARS-CoV and MERS-CoV [2] . Although most earlier cases had been confined 5 to mainland China, notably Hubei Province, a considerable number of people have been 6 infected all over the world since, and the WHO characterized the outbreak as a 7 pandemic on March 11 [1] . As of March 17, over 179,000 have been confirmed to be 8 infected, with almost 7400 deaths [3] . 9 As the Coronavirus contagion develops, with its rapid spread inciting concerns over 10 the epidemic's global impact, it is increasingly important to understand the dynamics of 11 the disease. Its severity is best described by two concepts: its ability to spread and its the average number of people to whom an infected person spreads the disease to [4] . Its 14 Case Fatality Rate (CFR) reveals the proportion of people who die from disease among 15 all individuals who contract the disease [5] . 16 Knowing the CFR is essential because it is the single most accurate metric to 17 appraise the threat posed by infectious diseases such as COVID-19 and predict its 18 prognosis. Although R0 is important to understand the rate of spread and 19 contagiousness, it does not describe the lethality of a disease. The case incidence would 20 describe the prevalence of the disease, but if it has a negligible CFR, the severity of the 21 disease is likely low. During the 2015 MERS outbreak in South Korea, there were only 22 186 cases, but the number of fatalities that resulted (38) was an adequate cause for 23 alarm [6] . Thus, the CFR, if calculated correctly, can help inform the appropriate 24 measures to control the epidemic.