Men have a higher risk of death than women if they contract the new strain of coronavirus, Chinese researchers concluded in the largest study on the outbreak to date.
In research published Monday, analysts studied 72,314 patient records from the Chinese Center for Disease Control and Prevention.
The records detailed 44,672 confirmed cases of the coronavirus, 16,186 suspected cases and 889 cases where the carrier of the coronavirus displayed no symptoms. Patients were categorized into three groups depending on whether their symptoms were mild, severe or critical.
The vast majority of confirmed cases were recorded in people ages 30 to 69, according to the research. Most of those diagnosed with the coronavirus — formally named COVID-19 — had reported "Wuhan-related exposures," while 81% of the confirmed cases were classified as mild.
According to the findings, just 4.7% of the confirmed cases had reached "critical" status, meaning patients had exhibited symptoms like respiratory failure, septic shock and multiple organ dysfunction or failure. However, half of the cases categorized as critical had turned fatal, the data showed.
The CCDC data also suggested that fatality rates were higher among men than women. Officials recorded a 2.8% fatality rate for male patients versus 1.7% for women.
Male patients accounted for 22,981, or 51%, of the total confirmed cases, while the coronavirus had been confirmed in 21,691 female patients as of Feb. 11, when the data collection ended.
Simon Clarke, associate professor in cellular microbiology, said Tuesday the statistical difference in the sexes may not be because of biology.
"It might be down to the sort of men and women included in the analysis; it might be the patients' exposure to situations that would put them at risk — it might not be an underlying biological reason," he told CNBC. "You have to be able to exclude all sorts of other social factors in order to be able to say there's a real biological difference — it could be down to circumstance."
Who is most at risk of coronavirus?
Elderly people and those with preexisting health conditions were most at risk of contracting a fatal case of COVID-19, researchers also noted.
Case fatality rate increased with age, with 14.8% of cases in people over age 80 resulting in death. Patients ages 70 to 79 had an 8% fatality rate, while those 60 to 69 had a fatality rate of 3.6%.
Researchers calculated an overall fatality rate of 2.3%, with a total of 1,023 deaths recorded among the confirmed cases of the virus in the study.
Cardiovascular disease was the preexisting condition most associated with increased fatalities, with the study reporting a fatality rate of 10.5% in patients who suffered with the condition. Diabetes sufferers had a fatality rate of 7.3%, while the frequency of fatalities was also higher than the overall rate in people with chronic respiratory disease, hypertension and cancer.
In patients with no reported underlying conditions, the fatality rate dropped to 0.9%, according to the study.
"Among the 1,023 deaths, a majority have been (over) 60 years of age and/or have had pre-existing … condition," the researchers said in the report. They highlighted that only those identified as having critical symptoms had died, and that the virus had not proved fatal for anyone in the "mild" or even "severe" categories.
However, the study's fatality rate — which was reached by dividing the total number of deaths by the number of confirmed cases — does vary from other calculations. Some experts believe the total number of coronavirus cases could be much higher than the records show, which would make the mortality rate lower than currently estimated.
"Because in most people it's relatively mild, we don't know how many people have COVID-19. The possibility remains that a lot of people have it and don't know they have it," Clarke said. "But we don't know that, and unless we screen populations on a large scale there's no way of knowing."
Speaking to CNBC's "The Exchange" last week, Dr. Ian Lipkin of Columbia University said it wasn't possible for an official mortality rate to be determined because of variables such as an unknown number of asymptomatic infections and varying diagnosis methods.
"My estimate is that the actual mortality rate is going to be lower, probably less than 1%," he said.
The new strain of coronavirus produces mild cold symptoms in about 80% of patients, a World Health Organization official told reporters last week. Around 15% of those who contracted COVID-19 ended up with pneumonia, while 3% to 5% of all patients needed intensive care, she said.
Chinese authorities said Tuesday there had been 1,886 new cases of the coronavirus on Monday, bringing the total number of cases confirmed on the mainland to 72,436.
While the number of deaths in Hubei province — the region at the epicenter of China's epidemic — were slightly lower from the previous day at 93, the research team behind Monday's study warned that "with many people returning from a long holiday, China needs to prepare for the possible rebound of the epidemic."