The mortality rate in Wuhan from COVID-19 is significantly lower than previously estimated, according to the findings of a recent study published in the journal Nature Medicine. Researchers noted that as of February 29, there was 79,394 confirmed cases and 2,838 deaths caused by COVID-19 in Mainland China – of which, 48,557 cases and 2,169 deaths occurred in the epicenter of Wuhan.
To conduct this study, the researchers expanded on previous transmission models and updated them with real-time data to “infer a preliminary set of clinical severity estimates that could guide clinical and public health decision-making as the epidemic continues to spread globally.” They noted that estimating true case numbers to determine the severity per case is challenging given that an overwhelmed health care system cannot effectively ascertain cases during a pandemic. They aggregated epidemiological data from publicly available data sources ( such as news articles, press releases and published reports from public health agencies) and estimated the Wuhan case numbers from only the first 425 cases to gauge the growth rate of the epidemic, while assuming that the ascertainment rate remained constant between December 10, 2019 and January 3, 2020.
According to the results, the overall probability of dying after developing symptoms of COVID-19 in Wuhan was 1.4% (0.9–2.1%), “which is substantially lower than both the corresponding crude or naïve confirmed case fatality risk (2,169/48,557 = 4.5%) and the approximator of deaths/deaths + recoveries (2,169/2,169 + 17,572 = 11%) as of 29 February 2020.” The researchers observed that compared to those aged 30–59 years, people younger than 30 and older than 59 years were 0.6 (0.3–1.1) and 5.1 (4.2–6.1) times more likely to die from COVID-19 after developing symptoms. Also, the findings showed the risk of symptomatic infection increased with age.
Harish Nair, Chair of Pediatric Infectious Diseases and Global Health at the University of Edinburgh, U.K., who also was not involved in the research, cautioned that the findings in this study may not be the same in other parts of the world. “I would advise caution when extrapolating from Chinese data to rest of the world or even to U.S., U.K. and Europe,” he said in a Newsweek article.
It has been hard to get reliable estimates of symptomatic case fatality rates and clinical severity. This new @NatureMedicine report is the best yet, sCRF of 1.4% and marked severity increase w/ age https://t.co/5viULrB1cC
Joseph Wu @gmleunghku @mlipsitch and colleagues pic.twitter.com/wVtFfuF28R
— Eric Topol (@EricTopol) March 19, 2020
“In developing countries where testing is very poor and majority deaths occur at home, this could be several-fold higher than in China,” he continued. “A lot of these data are from patients in higher socio-economic strata, where intensity of contact is less than what we would see in urban slums, proportion of diagnosed and well-managed co-morbidities and nutritional status [is] very different from [a low and middle-income] population. So, to me this estimate is optimistic and represents best case scenario.”
Estimating clinical severity of #COVID19 from the transmission dynamics in Wuhan, China https://t.co/by7ZjmzSrr
— Global Health Observ (@GlobalPHObserv) March 19, 2020
Estimating clinical severity of COVID-19 from the transmission dynamics in Wuhan, China by Wu et al. via Nature Medicine.https://t.co/0sppaEdaVa
— Dr.Martin-Moreno (@JMMartinMoreno) March 19, 2020