Death rate lower than estimates: Study
NEWDELHI: A new analysis of data from at least 70,000 lab-confirmed cases of coronavirus disease (Covid-19) from China puts the death rate at 1.38%, lower than earlier estimates ranging between 2% and 8% but higher than previous pandemics such as H1N1 influenza, which killed around 0.02% of the people infected in 2009-10.
The study, published in The Lancet Infectious Diseases journal on Monday, warned that 50% to 80% of the global population could get infected with Covid-19, and without interventions such as lockdowns and social distancing, the number of sick people needing hospital treatment could overwhelm even the most advanced health care systems. It, however, said that outcomes may change as the pandemic unfolds and evolves.
According to the study, by UK researchers from Imperial College London, Queen Mary University, London, and the University of Oxford, the death rates from confirmed Covid-19 cases came to 1.38%, and the overall death rate to 0.66% after adjusting for undiagnosed cases and population size (not included in earlier studies), according to the analysis of data from 70,117 laboratory-confirmed and clinically diagnosed cases in mainland China, combined with 689 positive cases among people evacuated from Wuhan on repatriation flights.
The death rates varied substantially with age, ranging from a low 0.0016% for people up to nine years old to 7.8% for people aged 80 and above. Previous studies have estimated the death rates in people over the age of 80 years to be between 8% and 36%.
While previous estimates of deaths from confirmed cases ranged from 2% to 8%, deaths from overall infections were estimated to be between 0.2% and 1.6%. Since the past estimates were not adjusted for the fact that only people with more severe symptoms are likely to be
tested, and the people in quarantine following repatriation to other countries, the numbers did not reflect the true number of cases across populations, some experts said.
“Estimated death rates of Covid-19 will vary based on how many infected people are entered into the denominator while deaths are in the numerator. While deaths are easier to verify and attribute, the num
ber of infected cases will vary according to the numbers tested with virus specific tests or identified on clinical criteria. Even if these are very liberally applied, we still may not define the denominator precisely as asymptomatic or very mild cases may escape detection by either criterion,” said Dr Srinath K Reddy, president, Public Health Foundation of India.
Death on average occurred
17.8 days after getting infected, and hospital discharge happened after 24.7 days, the study found. The proportion of deaths from both diagnosed cases and from milder, unconfirmed cases was strongly influenced by age.
“Our estimates can be applied to any country to inform decisions around the best containment policies for Covid-19,” said Professor Azra Ghani from Imperial College in a statement.