When the man finally went to a hospital, he had been sick for a week. It was Dec. 26, and Mr. Zeng, 61, was weak with a cough. He got worse. A day later he was transferred to intensive care and on Dec. 30 he was put on a ventilator to help his deteriorating ability to breathe.
He was moved to another hospital and attached to another machine that oxygenated his blood. Still he got worse, and on Jan. 9, his heart stopped. Mr. Zeng, who the authorities have only identified by his last name, became the first confirmed death from the new coronavirus that emerged in the central city of Wuhan and has spread around the country and beyond.
China’s health commission, which has tightly controlled news about the toll of the outbreak, on Thursday released the most complete details about the 17 confirmed deaths from the disease. The information was released as the authorities canceled transportation from Wuhan and largely blocked residents from leaving.
The details were revealed as medical experts have questioned whether the measures in Wuhan have come too late to prevent the spread of the coronavirus, which has been found in infected travelers in Washington state, Japan, South Korea, Thailand and Taiwan.
Dr. Guan Yi, a professor of infectious diseases at the University of Hong Kong who visited Wuhan earlier this week, warned there was a potential for the virus to spread rapidly despite the controls put in place Thursday morning.
“We have a chance to have a pandemic outbreak,” said Dr. Guan, who was part of the team that identified the coronavirus that caused the deadly SARS outbreak in 2002 and 2003. SARS infected more than 8,000 people and killed nearly 800.
Dr. Guan also told Caixin, an influential Chinese magazine known for its investigative reports, that he had traveled to Wuhan earlier in the week hoping to help track the virus’s animal source and control the epidemic. But he left, he said, feeling “powerless, very angry.”
Dr. W. Ian Lipkin, an epidemiologist at Columbia University who advised the Chinese government and the World Health Organization during the SARS outbreak, said that infected people outside Wuhan would continue to spread the disease.
“The horse is already out of the barn,” he said.
An examination of the information provided by the government about the 17 reported deaths show a disease that has thus far largely killed older men, many of whom had underlying health problems.
Most had gone to the hospital with a fever and a cough, though at least three did not have fevers when they were admitted, according to the health commission’s statement.
The victims include 13 men and four women. All were identified only by their last names. The youngest was a 48-year-old woman, Yin, who died on Monday, more than a month after her symptoms were first recorded. The oldest cases were two 89-year-old men who died on Saturday and Sunday.
Many had underlying conditions like cirrhosis of the liver, hypertension, diabetes and Parkinson’s disease.
While much about the virus remains unknown, medical experts found some positive signs in the fact that the disease did not appear to be killing young and otherwise healthy people.
It was a somewhat reassuring sign, Dr. Lipkin wrote, that “the majority of fatal cases are elderly and/or have a chronic disease that would increase their susceptibility to infectious diseases.”
Javier Hernández and Amber Wang contributed reporting.