More than 80 percent of the novel coronavirus cases were mild infections. But the virus proved fatal for elderly patients with multiple medical conditions, said the biggest-ever study related to the epidemic by Chinese Center for Disease Control and Prevention (CCDC).

A large number of deaths were reported in the age group of 80 and above, which had the highest mortality rate at 14.8 percent. 

In Hubei Province, the worst affected region, overall mortality rate stood at 2.9 percent and in other provinces 0.4 percent. As a whole, the death rate for the virus stood at 2.3 percent, according to the findings released Tuesday.

"Among the 1,023 deaths, the majority have been above 60 years of age and/or have had pre-existing, co-morbid conditions [one or more medical conditions] such as hypertension, cardiovascular disease, and diabetes," wrote the researchers in the study.

Data from 72,134 coronavirus patients, including more than 40,000 confirmed and nearly 16,000 suspected cases reported till February 11, were used by the CCDC researchers.  

The finding is hoping to fill crucial research gaps and unknowns related to the new strain of the virus. "The virus is highly contagious," the study added.

The World Health Organization (WHO) alarmed over the scale of transmission within China, especially in Hubei Province, spreading to other countries, declared the epidemic a Public Health Emergency of International Concern (PHEIC). But it refrained from issuing any travel and trade advisory. 

Medical staff facing the brunt

Front-line medical staff working tirelessly in 422 health facilities are facing one of the worst impacts of the epidemic. 

Out of 3,109 health workers suspected to be infected with the virus, around 1,716 were confirmed cases. Six of them died. 

The epidemic peak among health workers was reached on February 1, the data suggested. The infection among medical workers started witnessing a sharp decline from 45 percent in early January to 8.7 percent in early February, the study elaborated. 

Within a few weeks, critical cases among the health workers declined from 38.9 percent in early January to 12.7 percent in early February.

Amid the falling rate of infection, a wave of sadness gripped medical professionals, with the death of Liu Zhiming, director of Wuchang Hospital in Wuhan, the epicenter of the outbreak, on Tuesday. Liu contracted the virus while treating infected patients.

The data also revealed a high mortality rate among males at 2.8 percent versus 1.7 percent for women. Male patients accounted for 51 percent, or 22,981, of the infection cases.

The epidemic curve shows that there was "a continuous common source" of transmission of the virus in December and then from early January through February 11.

Researchers suspect the occurrence of several zoonotic events at Huanan Seafood Market from where the virus originated from an unknown animal and passed on to humans. In the following weeks, the virus may have mutated, leading to human-to-human transmission.

Many experts confirmed bats hosted the new coronavirus. Still, for passing on to humans, it requires an intermediary host. Recent researches suspect snakes or pangolins.

According to the study, the epidemic is getting weak, but challenges remain. As a large number of people will soon be returning to work and school after the extended Lunar New Year holidays, a rebound of the epidemic might happen in the coming weeks, they warned. 

(Top image: Hospital staff wash the emergency entrance of Wuhan Medical Treatment Center, where some infected with a new virus are being treated, in Wuhan, China, January 22, 2020. /AP)