Ai Fen, director of Wuhan Central Hospital's emergency department, shared a diagnostic report with colleagues on WeChat on December 30. She was particularly concerned by the similarities between the new pneumonia-like infection and SARS, she told Chinese magazine, People.

A hospital supervisor criticized Ai for "spreading rumors" and forbade her from speaking about it even to her family, the South China Morning Post said.

Hospital staff saw person-to-person transmission long before officials acknowledged or reported it, leaving " hundreds of doctors and nurses in the dark, doing all they could to treat patients without knowing about the epidemic," the Chinese outlet Caixin reported.

Frontline healthcare workers at Wuhan Central Hospital were among the worst hit by the COVID-19 virus. Four among them, including whistleblower doctor Li Wenliang, have died.

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A Wuhan doctor said she wishes she could rewind the clock to December when she first sounded the alarm about a new pneumonia-like virus — only to back away after being reprimanded by Chinese officials.

Ai Fen, director of Wuhan Central Hospital's emergency department, told Chinese magazine People that a colleague sent her a diagnostic report in late December of a worrying infection that mirrored severe acute respiratory syndrome (SARS), according to the South China Morning Post.

Ai shared a picture of the report on a WeChat group on December 30, and then its members circulated that photo more widely. Whistleblower doctor Li Wenliang, 34, who was silenced by Chinese officials and then died of the COVID-19 virus, was part of that group.

Ai said she also gave hospital authorities a heads-up about the virus.

"I even grabbed our hospital respiratory department director, who happened to be passing my office, and told him that one of his patients was confirmed to have been infected with a SARS-like virus," Ai said to People magazine, the Post reported.

'My mind just went blank'

The next day, hospital leaders told Ai that Wuhan's health commission had forbidden frontline medical workers from saying anything about the virus in a bid to avoid panic.

Ai said she was also censured by a hospital official, who accused her of "spreading rumors," the Post reported. She was ordered to not speak about it even to her husband and to inform her staff members that they were not permitted to publicly disclose any information about the illness.

"My mind just went blank," Ai told the magazine. "He wasn't criticizing me for not working hard … He made me feel that I alone had ruined the future of Wuhan. I was in despair."

Li Wenliang wears a respirator mask, following the coronavirus outbreak, in Wuhan, China, February 3, 2020. LI WENLIANG/GAN EN FUND via REUTERS

One week later, a hospital nurse, Hu Ziwei, fell sick, Ai said.

"How could I refrain from discussions with my medical colleagues knowing that a new and significant virus had emerged? I followed my intuition as a doctor so what mistakes did I make?" Ai wondered.

Evidence of human-to-human transmission

It has been widely reported that the coronavirus originated in a wet market in Wuhan, and Ai said initial patients were in some ways linked to the market. But, soon that trend changed, and more family clusters began to show up.

"If there's no people-to-people transmission, why did the patients continue to increase after the Huanan market was closed?" Ai said.

An investigation from the Chinese outlet Caixin found that more than 230 of 4,000 staff members at the Wuhan Central Hospital have contracted the coronavirus. This is the highest rate of infection at all Wuhan medical centers.

Dr. Li Wenliang died in February and was followed by other doctors Jiang Xueqing and Mei Zhongming in early March. Ophthalmologist Zhu Heping died on March 9, marking the fourth fatality among medical workers.

The hospital's deputy chief cardio-thoracic surgeon and deputy chief urologist are in critical condition, a head nurse told Caixin.

Frontline medical staff were kept 'in the dark'

A department head who asked to stay anonymous told Caixin that Chinese authorities have risked people's lives by spreading misinformation.

"The false information released by the relevant departments — claiming the disease was controllable and would not spread from human-to-human — left hundreds of doctors and nurses in the dark, doing all they could to treat patients without knowing about the epidemic," the source said. "And even when they fell ill, they could not report it. They could not alert their colleagues and the public in time despite their sacrifice. This is the most painful loss and lesson."

Doctors at Wuhan Central Hospital also pointed to other factors that put them at heightened risk, Caixin reported.

Poultry vendor selling live chicken at wet market in Kowloon City. Felix Wong/South China Morning Post via Getty Images

To start, they were at close proximity to the South China Seafood Market, where a majority of early cases are believed to have sparked. First-generation virus infections are likely more lethal, Caixin said. Li and Mei reportedly contracted the virus from the same patient.

Also, early January saw a large number of patients come to the hospital with elevated temperatures. At the time, another local hospital was treating only those coronavirus patient who had in some way come in contact with the seafood market. All others were being shipped off to the Central Hospital where staff were not experts in contagious diseases and so got sick.

Interfering with diagnoses

Meanwhile, doctors were not allowed to report cases that they encountered.

"It's fairly easy to fill out the disease reporting form," a doctor told Caixin. "When we get cases of hepatitis B or other severe infectious diseases, we can make a diagnosis directly on the computer, fill in the infectious disease report in a pop-up window and just click OK." But "to do that, a diagnosis must be made," the doctor said.

A law enforcement official visited the hospital on January 12, Caixin reported, and told medical staff that the infectious disease forms could only be completed and submitted with guidance from experts at the city and provincial levels.

The next day, Wang Wenyong, who leads infectious disease control at Wuhan's Jianghan district disease control center, told Wuhan Central hospital to alter a suspected coronavirus report to say that patients were suffering from other illnesses.

And the district health authority, rather than collecting samples and consulting with the hospital, asked medical staff to wait, causing an ill-afforded delay, doctors said to Caixin. And all the while, patients poured in and the number of cases continued to climb.

A doctor examines a patient who is infected by the coronavirus at a hospital in Wuhan in China's central Hubei province. STR/AFP via Getty Images

'I would have told everyone, even though I was warned'

Now, Ai says she "really regrets" not telling more people about what she was seeing because her fellow doctors may not have died if they "could have been warned earlier," according to the Post.

"As a clinician, when I discover a very important virus, how could I not tell other doctors… I did the thing that a doctor, a normal human being would do," said Ai. "If the public could be alert for the virus since Jan. 1, then there would not be so many tragedies."

The censoring that Ai complained about continued into this week, Quartz reported, with her article being deleted from People's WeChat page.

However, Chinese WeChat users, who rallied for freedom of speech after Wenliang's passing, defied censors by writing the story backward, inserting emojis and Braille symbols, and even using a coded, so-called "Martian" language that relies on ancient Chinese characters. Translated to English and German, the article was re-shared to WeChat, only to be taken down again, Quartz found.

For her part, Ai said if she had known how the coronavirus would go on to infect more than 127,000 people and kill over 4,700 others, "I would have told everyone, even though I was warned," she said. "I have thought many times: if only time could be turned back."