At least 500 hospital staff in Wuhan had been infected with the deadly new strain of coronavirus by mid January, multiple medical sources have confirmed, leaving hospitals short-staffed and causing deep concern among health care workers.
While the government has reported individual cases of health care workers becoming infected, it has not provided the full picture, and the sources said doctors and nurses had been told not to make the total public.
The reason for this edict was not explained, but the authorities have been trying to boost morale among frontline medical staff, especially following the death of Li Wenliang, who was killed by the disease weeks after being reprimanded by police for warning colleagues about the new virus.
A slide circulating online, however, reveals the scale of infections among medical workers in Wuhan.
It said that by mid-January there had been about 500 confirmed cases among hospital staff with a further 600 suspected ones.
A source from a major hospital in Wuhan with knowledge of the situation confirmed that the slide was authentic.
The figures shown on the slide were also in line with the figures given by two other doctors from major hospitals in Wuhan.
Those infected included at least 100 staff from both Wuhan Xiehe Hospital and Renmin Hospital of Wuhan University, with a further 50 cases each from Wuhan Number 1 Hospital and Zhongnan Hospital.
A research paper published by doctors from Zhongnan Hospital in The Journal of the American Medical Association last Friday said at least 40 medical workers had been infected.
Apart from hampering the capacity of hospitals to contain the outbreak and treat patients, medical specialists said the rate of infections among frontline staff was an important indicator of how easily the disease, which has killed more than 1,000 people, could be transmitted and the risks of contracting the virus in hospital.
A doctor from a major hospital in Wuhan, who requested anonymity, said the development had hit morale, adding that many medical workers were "devastated" when they saw the CAT scans of colleagues who had been infected.
"That is why we have been crying out for more donations of medical supplies, especially hazmat suits," one doctor said, describing how a quarantine area set aside for sick medical workers was now full. "We have seen too many colleagues falling ill because of insufficient protection."
Doctors and medical experts have said that a shortage of protective gear, overlong working hours and well as lack of awareness about how contagious the virus was had been major factors in the large number of infections.
Yu Changping, a respiratory specialist with the Renmin Hospital of Wuhan University, developed a fever on January 14 and was later confirmed to have contracted the virus.
He said he was not sure when he became infected since he treated many patients every day and the chance of getting infected was high.
"The virus is too contagious. We did not have enough understanding about the virus," he said.
Yu was admitted to hospital on Jan 17 with another colleague from the same department and is still being treated.
The deaths of at least three Wuhan health care workers have been reported so far - including that of Li, whose case triggered national storm of outrage about initial attempts to cover up the outbreak.
The deputy director of Li's department, Mei Zhongming, is also reported to have become infected.
It is also unknown if any patient was infected by sick health care workers.
According to Li's own posts on the social media network Weibo, he contracted the disease on January 8 from a patient, but only started showing symptoms two days later.
Ian Lipkin, John Snow professor of epidemiology at the Mailman School of Public Health at Columbia University, said the risks faced by health care workers were high even with protective gear.
"The reason for this is that physicians and health care workers have a very intimate relationship with their patients, and even with personal protective equipment, sometimes we use it late, sometimes we get exposed inadvertently, and the efforts we make to support them with fluids and such place us at extremely high risk," he told a briefing on Sunday after visiting China at the invitation of the government.
"In addition, those individuals who are working in hospital settings may be immunosuppressed because frankly they're exhausted… the viral load that they receive may be larger."
A second doctor from a major hospital said health care workers also had to face dire shortages of manpower because many have fallen sick.
"Just a very rough estimate, 100 nurses and doctors can look after 100 ordinary beds and 16 ICU beds. If they are sick, not only do they occupy 100 beds, but the staff taking care of 100 beds are gone. That means a hospital loses the capacity of 200 beds."
"That is why the authorities have to keep sending medics over to Wuhan, not only because there are not enough beds, but because of a lack of health doctors and nurses to take care of the sick beds."
The Chinese authorities have mobilised around 10,000 additional medical staff to treat patients in Wuhan, the epicentre of the outbreak, and more protective gear has been sent to major hospitals in the city.
But frontline doctors warned of that health care workers in other cities, especially those with less attention and supplies, faced a higher infection risk.
"Infections among health care workers are now less serious than in January," one of the Wuhan doctors said. "The biggest concern is protective gear, but as long as there is gear, it is unlikely we will get infected."
But the doctor warned that the situation may be worse in other cities in Hubei province and said he had heard that many health care workers in the neighbouring city of Ezhou had been infected.
Hospital clusters have also been reported in different parts of the country. In the island province of Hainan, the local health commission said a doctor and nurse had become infected after being exposed to a patient for six minutes even though they were wearing masks.
In Fuxing hospital in Beijing, six medical staff, five patients and four caretakers were reportedly infected by a patient. A source said the hospital's president Li Dongxia had been sacked as a result.
Zhang Ke, a doctor at Beijing's Youan hospital, which specialises in communicable diseases, said cross infections between patients and doctors were a serious concern, particularly as many hospital wards were not designed to handle communicable diseases.
"Even in designated hospitals, receiving and treating patients was quite chaotic in Wuhan. Fever patients rushed to hospital and they hospitals became an incubator for the virus because their design is less scientific than that of the communicable disease hospitals."
"During the SARS outbreak in 2003, 18 per cent of mainland medical staff and 22 per cent of Hong Kong medical staff were infected. I estimate we will see 10-20 per cent of medical staff infected," he said.
For the latest updates on the coronavirus, visit here.
This article was first published in the South China Morning Post.