An average coronavirus patient may be in hospital for about 25 days and the mean duration from the onset of symptoms to death is about 18 days, a study in The Lancet Infectious Diseases has said. The study also concluded that the overall infection fatality rate for China, where coronavirus first hit, was 0.66%, though adding that it remained a major global crisis.
Researchers from Imperial College, London, had earlier said that the ‘crude fatality ratio’ was about 3.67%, which is on a par with WHO estimates. The crude rate does not take into account the severity of the infection, which means it just compared the total number of cases with the total number of deaths. Infection fatality ratio takes into account the total number of people that might carry the virus, without showing symptoms and hence being tested for it or requiring hospitalisation. These people are not a part of the official number of “cases”.
As per the Lancet study, severity of coronavirus depends on the age of a patient, and the overall case fatality ratio (number of deaths per positive cases) could be 1.38%. In those above 60 years, it was found to be 6.4%; in those above 80 years, 13.4%; and in people aged below 60 years, 0.32%.
The Lancet study, that came out on Tuesday, said, “Using data on 24 deaths that occurred in mainland China and 165 recoveries outside of China, we estimated the mean duration from onset of symptoms to death to be 17·8 days and to hospital discharge to be 24·7 days. In all laboratory confirmed and clinically diagnosed cases from mainland China (70,117), we estimated a crude case fatality ratio (adjusted for censoring) of 3·67%. However, after further adjusting for demography and under-ascertainment, we obtained a best estimate of the case fatality ratio in China of 1·38%, with substantially higher ratios in older age groups (0·32% in those aged <60 years vs 6·4% in those aged =60 years), up to 13·4% in those aged 80 years or older.”
Outlining the implications of the study, the researchers said, “Our estimates of the case fatality ratio for COVID-19, although lower than some of the crude estimates made to date, are substantially higher than for recent influenza pandemics (eg, H1N1 influenza in 2009). With the rapid geographical spread observed to date, COVID-19 therefore represents a major global health threat in the coming weeks and months. Our estimate of the proportion of infected individuals requiring hospitalisation, when combined with likely infection attack rates (around 50-80%), show that even the most advanced health-care systems are likely to be overwhelmed. These estimates are therefore crucial to enable countries around the world to best prepare as the global pandemic continues to unfold.”
Till April 1, 8.53 lakh cases of COVID-19 had been reported world-wide, with 41,887 deaths. China has seen 82,295 cases and 3,310 deaths.
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