"He had identified the virus. It was a new coronavirus. And it was not highly transmissible. This didn't really resonate with me because I'd heard that many, many people had been infected," Lipkin told the BBC. "I don't think he was duplicitous, I think he was just wrong."
Epidemiologist Ian Lipkin
Lipkin says he thinks Gao should have released the sequences they had already obtained. My view is that you get it out. This is too important to hesitate."
Gao, who refused the BBC's requests for an interview, has told state media that the sequences were released as soon as possible, and that he never said publicly that there was no human-to-human transmission.
That day, the Wuhan Health Commission issued a press release stating that 27 cases of viral pneumonia had been identified, but that there was no clear evidence of human to human transmission.
TV channel CGTN reporting 27 cases of "viral pneumonia"
It would be a further 12 days before China shared the genetic sequences with the international community.
The Chinese government refused multiple interview requests by the BBC. Instead, it gave us detailed statements on China's response, which state that in the fight against Covid-19 China "has always acted with openness, transparency and responsibility, and … in a timely manner."
BBC This World's 54 Days: China and the pandemic can be seen on BBC Two at 21:00 GMT on Tuesday 26 January, or 23:30 on Monday 1 February (except BBC Two Northern Ireland). Or watch on BBC iPlayer.
Part two - 54 Days: America and the Pandemic - will be on BBC Two on Tuesday 2 February at 21:00.
A BBC/PBS Frontline co-production.
1 January 2020: International frustration
International law stipulates that new infectious disease outbreaks of global concern be reported to the World Health Organization within 24 hours. But on 1 January the WHO still had not had official notification of the outbreak. The previous day, officials there had spotted the ProMed post and reports online, so they contacted China's National Health Commission.
"It was reportable," says Professor Lawrence Gostin, Director of the WHO Collaborating Center on national and global health law at Georgetown University in Washington DC, and a member of the International Health Regulations roster of experts. "The failure to report clearly was a violation of the International Health Regulations."
Dr Maria Van Kerkhove, a WHO epidemiologist who would become the agency's Covid-19 technical lead, joined the first of many emergency conference calls in the middle of the night on 1 January.
"We had the assumptions initially that it may be a new coronavirus. For us it wasn't a matter of if human to human transmission was happening, it was what is the extent of it and where is that happening."
Dr Maria Van KerkhoveIt was two days before China responded to the WHO. But what they revealed was vague - that there were now 44 cases of viral pneumonia of unknown cause.
China says that it communicated regularly and fully with the WHO from 3 January. But recordings of internal WHO meetings obtained by the Associated Press (AP) news agency some of which were shared with PBS Frontline and the BBC, paint a different picture, revealing the frustration that senior WHO officials felt by the following week.
"'There's been no evidence of human to human transmission' is not good enough. We need to see the data," Mike Ryan WHO's health emergencies programme director is heard saying.
The WHO was legally required to state the information it had been provided by China. Although they suspected human to human transmission, the WHO were not able to confirm this for a further three weeks.
"Those concerns are not something they ever aired publicly. Instead, they basically deferred to China," says AP's Dake Kang. "Ultimately, the impression that the rest of the world got was just what the Chinese authorities wanted. Which is that everything was under control. Which of course it wasn't."
2 January: Silencing the doctors
The number of people infected by the virus was doubling in size every few days, and more and more people were turning up at Wuhan's hospitals.
But now - instead of allowing doctors to share their concerns publicly - state media began a campaign that effectively silenced them.
On 2 January, China Central Television ran a story about the doctors who spread the news about an outbreak four days earlier. The doctors, referred to only as "rumour mongers" and "internet users", were brought in for questioning by the Wuhan Public Security Bureau and 'dealt with' 'in accordance with the law'.
One of the doctors was Li Wenliang, the eye doctor whose warning had gone viral. He signed a confession. In February, the doctor died of Covid-19.