A man rides a bicycle with the US Capitol Building in the background in Washington D.C., the United States, on April 21, 2020. (Xinhua/Liu Jie)

Chinese scientists on Friday urged a thorough investigation into the early stages of the coronavirus outbreak in the US with the participation of the World Health Organization (WHO), after two people in the US state of California who died in early and mid-February were found to have been killed by COVID-19, weeks earlier than the previously known first death of the virus in the country. 

Such a probe will likely encounter roadblocks from the US, which has been relentlessly pushing a narrative of the virus coming from China and repeatedly attacking the WHO in an apparent attempt to shift blames for its failure to stem the virus. But scientists urged the US to act responsibly and transparently and cooperate in the probe to help the world better understand the virus - the real mission to beat back the common enemy rather than political scapegoating.

New autopsy results from Northern California's Santa Clara county on Tuesday showed two residents in the county in California died of novel coronavirus in February, weeks before what was believed to be the country's first reported death, CNN reported Wednesday. 

The development appears to have shifted the understanding of how early the virus was spreading in the country, US health experts told CNN.

The two were a 57-year-old woman, Patricia Dowd, who died in her home in the county on February 6, and a 69-year-old man who died at home in the same county on February 17, US officials said. What was previously thought to be the US' earliest death happened on February 29 in Kirkland, Washington.

The two in California had no "significant travel history" that would have exposed them to the virus, Sara Cody, the county's chief medical officer, told CNN Wednesday in San Jose. 

The New York Times reported that Dowd had traveled all over for her job such as Germany and Austria and "at times" to China but noticeably did not offer a specific timeline.

Zeng Guang, chief epidemiologist at the Chinese Center for Disease Control and Prevention, told the Global Times on Friday that there could be even earlier cases of deaths from COVID-19, so a thorough investigation will be critical in determining an origin for the virus. 

"During the winter last year, even before the outbreak in China occurred, the seasonal influenza hit the US badly and killed many people. For the timeline, it is connected to the earliest deaths of COVID-19 in the US, so it is not just Chinese scientists like myself who have questions about who was the real patient zero in the country. The US public and experts also hope that the US government will provide a clear answer," Zeng said.

Medical workers carry a patient into an ambulance in New York, the United States, April 6, 2020. (Photo by Michael Nagle/Xinhua)

The death toll in the US from the coronavirus topped 49,000 as of the press time as the number of confirmed cases hit more than 869,000. 

Yang Zhanqiu, deputy director of the Pathogen Biology Department at Wuhan University, told the Global Times that with the two now standing as the country's first documented fatalities attributed to the virus, it would not be surprising if some cases in late 2019 that were diagnosed as influenza in the country were connected to the coronavirus.

"If the coronavirus had spread in late 2019 in the country, then it's reasonable that the two cases died of the virus with no significant travel history," Yang said.

Ashish K. Jha, director of the Harvard Global Health Institute, also told CNN the finding was significant. 

"We really need now to go back, look at a lot more cases from January - even December - and try to sort out when did we first really encounter this virus in the United States," Jha said.

US leaders and senior officials like President Donald Trump and Secretary of State Mike Pompeo have continually blamed China and the WHO, and even tried to make the G7 members pressure the WHO, but have failed. This attitude makes international cooperation to investigate the US outbreak very difficult, and the US government might not be very motivated to seek out the facts as it has political concerns, Chinese analysts have said.

"Finding the origin is not for compensation or to make any country pay for the pandemic, but to serve the purpose of science. The US has isolated itself from the international community many times before COVID-19 on other global issues, so we hope this time it can treat the pandemic with a scientific attitude," Zeng said.

Zeng noted that it would not be hard for the US to investigate through tracking the samples of "influenza patients" in December and January to find out how many of them were misdiagnosed since the US has a very mature and advanced system that keeps this data and samples.

"Even if the final results showed that the origin of the novel coronavirus was the US, no country in the international community would ask the US for compensation as the consensus in the international community is that the country of origin is not a criminal but rather the first victim of the pandemic," he said.

Asked to comment on research results which suggested the COVID-19 may have broken out in the US in the beginning of the year, Chinese Foreign Ministry Spokesperson Geng Shuang said at a routine press conference on Friday that the question should be answered by the US government. 

The origin of COVID-19 and the path of infection are very complicated scientific questions, Geng said at the same conference, in response to another question to comment on reports that the earliest confirmed case in Australia could have come from the US.

Before scientists worldwide reach a final conclusion, any non-professionals should not come to conclusions as this is irresponsible and won't benefit international cooperation at all, he said, noting that the epidemic knows no border or race, and is the common enemy of mankind.