Health officials in China have published the first details of more than 70,000 cases of Covid-19, in the biggest study since the outbreak began.
Data from the Chinese Centre for Disease Control and Prevention (CCDC) found that more than 80% of the cases have been mild with the sick and elderly most at risk.
The research also points to the high risk for medical staff.
The findings put the overall death rate of the Covid-19 virus at 2.3%.
In Hubei, the worst affected province, the death rate is 2.9% compared with only 0.4% in the rest of the country.
China’s latest official figures released on Tuesday put the overall death toll at 1,868 and 72,436 infections.
Officials said there were 98 new deaths and 1,886 new cases in the past day, 93 of those deaths and 1,807 of the infections were in Hubei province – the epicentre of the outbreak.
More than 12,000 people have recovered, according to Chinese authorities.
The paper by CDD, released on Monday and published in the Chinese Journal of Epidemiology, looked at all 72,314 cases of Covid-19 diagnosed across China as of 11 February, including confirmed, suspected, and asymptomatic cases.
While the results largely confirm previous descriptions of the virus and patterns of infection, the study includes a detailed breakdown of the 44,672 confirmed cases across all of China.
Some of the conclusions reached include the following:
Some 80.9% of infections are classified as mild, 13.8% as severe and only 4.7% as critical. Where by the highest fatality rate is for people aged 80 and older, at 14.8%.
For children up to 9, there have been no fatalities and up to the age of 39, the death rate remains low at 0.2%.
The paper also identified the next age groups, the fatality rates increase gradually: For people in their 40s it is 0.4%, in their 50s it is 1.3%, in their 60s it is 3.6% and their 70s it is 8%.
Looking at the sex ratio, men are more likely to die (2.8%) than women (1.7%).
Identifying which existing illnesses put patients at risk, the study finds cardiovascular disease at number one, followed by diabetes, chronic respiratory disease and hypertension