GENEVA (NYTIMES) - On a cold weekend in mid-February, when the world still harboured false hope that the new coronavirus could be contained, a World Health Organisation (WHO) team arrived in Beijing to study the outbreak and investigate a critical question: How did the virus jump from animals to humans?

At that point, there were only three confirmed deaths from Covid-19 outside China and scientists hoped that finding an animal source for the coronavirus would unlock clues about how to stop it, treat it and prevent similar outbreaks.

"If we don't know the source then we're equally vulnerable in the future to a similar outbreak," Michael Ryan, the WHO's emergency director, had said that week in Geneva. "Understanding that source is a very important next step."

What the team members did not know was that they would not be allowed to investigate the source at all.

Despite Ryan's pronouncements, and over the advice of its emergency committee, the organisation's leadership had quietly negotiated terms that sidelined its own experts. They would not question China's initial response or even visit the live-animal market in the city of Wuhan where the outbreak seemed to have originated.

Nine months and more than 1.1 million deaths later, there is still no transparent, independent investigation into the source of the virus.

Notoriously allergic to outside scrutiny, China has impeded the effort, while leaders of the WHO, if privately frustrated, have largely ceded control, even as the Trump administration has fumed.

From the earliest days of the outbreak, the WHO - the only public health body with a global remit - has been both indispensable and impotent. The Geneva-based agency has delivered key information about testing, treatment and vaccine science. When the Trump administration decided to develop its own test kits, rather than rely on the WHO blueprint, the botched result led to delays.

At the same time, the health organisation pushed misleading and contradictory information about the risk of spread from symptomless carriers. Its experts were slow to accept that the virus could be airborne. Top health officials encouraged travel as usual, advice that was based on politics and economics, not science.

The WHO's staunchest defenders note that, by the nature of its constitution, it is beholden to the countries that finance it. And it is hardly the only international body bending to China's might. But even many of its supporters have been frustrated by the organisation's secrecy, its public praise for China and its quiet concessions. Those decisions have indirectly helped Beijing to whitewash its early failures in handling the outbreak.

Now, as a new Covid-19 wave engulfs Europe and the United States, the organisation is in the middle of a geopolitical standoff.

China's leaders want to constrain the organisation; US President Donald Trump, who formally withdrew the US from the body in July, now seems intent on destroying it; and European leaders are scrambling to reform and empower it.

The search for the virus's origins is a study in the compromises the WHO has made.

On the surface, an investigation into the virus's origin is progressing. Beijing recently approved a list of outside investigators. The health organisation has agreed that key parts of the inquiry - about the first patients in China and the market's role in the outbreak - will be led by Chinese scientists, according to documents obtained by The New York Times. The documents, which have never been made public, show that WHO experts will review and "augment, rather than duplicate," studies undertaken by China.

Internal documents and interviews with more than 50 public-health officials, scientists and diplomats provide an inside look at how a disempowered WHO, eager to win access and cooperation from China, has struggled to achieve either. Its solicitous approach has given space for Trump and his allies to push speculation and unfounded conspiracy theories, and deflect blame for their own mistakes.

The organisation said it was committed to a full-scale investigation irrespective of political distractions.

"Divisions between and within countries have provided fertile ground for this fast-moving virus to grow and gain the upper hand," the WHO's director general, Tedros Adhanom Ghebreyesus, said in a statement to the Times.

The question of where Covid-19 began is especially intriguing because the initial theory, centred on illegal wildlife sales at the Wuhan market, is now in doubt.

There is powerful evidence that the new coronavirus passed naturally from an animal into humans. Scientists have found a virus in bats that is a close relative, and they suspect that it may have infected another animal species before it reached people.

But though they agree that many cases were linked to the market in Wuhan, many scientists no longer believe it is where the outbreak began.

For now, however, it's still where the trail goes cold.

A Contaminated Market

On the night of Dec 30, 2019, according to local reports, workers in protective gear began scrubbing the Huanan Seafood Wholesale Market in Wuhan, a warren of vendors selling produce, meats and wild animals. They scoured the market, going stall to stall, and spraying disinfectant to stop an outbreak that officials believed originated there.

A day or so later, another team arrived from China's Center for Disease Control and Prevention. According to one official account, the experts took samples both from products sold at the market and the environment.

But three weeks later, George F. Gao, the chief scientist at China's CDC, indicated to a reporter that the market had been closed before his team could conduct a thorough search for the animal source.

This is a key moment. The discrepancy in the accounts leaves open two possibilities. If researchers tested samples from live animals, then they may be concealing potentially important clues about the origins of the virus.

But if they arrived after the market had been closed and disinfected, they may only have taken samples from places like door handles, counters and sewage runoff.

Many outside experts consider this the most likely scenario. They said it was understandable that local officials, focused on preventing human illness, would rush to clean the market rather than pause to preserve evidence.

Yet that would mean that Chinese officials probably missed a chance to confirm where the outbreak did, or did not, originate.

In late January, Gao co-wrote one of the earliest epidemiological studies about the virus. The study highlights the market's links to the outbreak. But a close look at the data reveals something significant: Four of the first five coronavirus patients had no clear links to the market.

They had apparently been infected elsewhere.

The Diplomacy of Effusive Praise

In late January, Tedros met with China's leader, Xi Jinping, in Beijing. The outbreak was gathering speed, if still largely confined to China, as the two men sat in front of a bucolic mural in the Great Hall of the People and carved out an agreement.

Tedros had rushed to Beijing to lobby Xi to allow in a large team of international experts. A small WHO team had traveled to Wuhan a week before but had not gone to the market or to the largest hospital for infectious diseases.

Xi did not welcome the suggestion that China needed help. But he agreed to let a WHO mission evaluate the situation "objectively, fairly, calmly and rationally."

The agreement was critical for Tedros, who the previous week had decided against declaring an international emergency after convening a committee to advise him.

What was not publicly known, though, was that the committee's Jan 23 decision followed intense lobbying, notably by China, according to diplomats and health officials.

Committee members are international experts largely insulated from influence. But in Geneva, China's ambassador made it clear that his country would view an emergency declaration as a vote of no confidence.

Half the committee said it was too early to declare an emergency. The outcome surprised many countries, as did Tedros when he publicly praised both Xi and China's pneumonia surveillance system.

Praising China, though, has been Tedros' trademark refrain.

In the end, Tedros declared an emergency on Jan 30, on the advice of nearly every member of the committee, save for the Chinese delegate.

About a week later, in early February, two top experts from the organization went to Beijing to negotiate the mission's agenda. That same week, the world's leading health experts ranked finding the animal host as one of the top tasks.

Yet, even before the full team gathered in Beijing on Feb. 16, the WHO had ceded ground, according to two people who were on the mission, diplomats and others. It agreed not to examine China's early response or begin investigating the animal source, they said. It could not even secure a visit to Wuhan.

American Fury

In Washington, the US health secretary, Alex M. Azar II, gathered advisers inside a conference room of the Department of Health and Human Services to hear from two government scientists who had participated in the WHO mission to China.

The scientists, still in quarantine, described by videoconference the seemingly unimaginable lockdown that China had imposed. When questions turned to the origins of the virus, however, answers stopped.

"You'd have to look at the terms of reference," one of the scientists replied, a senior US health official recalled. The "terms of reference" was a document spelling out the mission's rules. The Americans had never seen it.

In the United States, where the pandemic was starting to take root, Trump and his allies began to talk about the "China virus." On April 7, Trump accused the WHO of being too close to China.

In May, under sharp criticism for his administration's response to the outbreak, Trump announced the U.S. would soon withdraw from the international organization. Doing so isolated him from allies who shared some of his frustrations but wanted to strengthen, not abandon, the WHO.

Bottlenecks

The WHO found new support in May for its stalled effort to investigate the virus's origins. A resolution, sponsored by more than 140 countries, included a clause directing the agency to search for the animal source.

By the summer, even the WHO was frustrated. Two experts who went to China in July to define the terms of the investigation spent two weeks in quarantine. They interviewed experts by phone but did not go to Wuhan.

Chinese officials then said that the organisation should start investigating in Europe.

In a letter to Chinese officials described to the Times, the health organisation expressed frustration at China's delays and insisted that the investigation begin in Wuhan, if only because the first infections were found there.

None of these frustrations spilled into public. The organisation described only progress. Yet it repeatedly declined requests by multiple governments to disclose the investigation terms it had negotiated with China. On Friday, the organisation told the Times that it would soon make the documents public.

An executive summary of the documents, obtained by the Times, shows that the health organisation's virus origin studies will unfold in two phases. One will look for the first patients by reviewing hospital records and interviewing people who were treated for the virus in December. The team will also investigate what wildlife was sold at the Wuhan market and follow the supply chain, according to the summary.

The WHO has agreed this phase will be led by Chinese scientists, with outsiders reviewing their work remotely.

In the second phase, international experts will work with Chinese colleagues to find the virus among animal hosts and a possible intermediate host.