This is one of the deadliest periods in modern history. Across the world, Covid is surging. Hospital beds are filling up. People are staying at home.

The World Health OrganisationThe United Nations agency responsible for global public health. has issued a dire warning: within eight weeks, half of Europe will have caught OmicronAn extremely contagious variant of Covid-19 first reported in November 2021..

The statistics are shocking. Today, the worldwide death toll stands at more than 5.5 million. In Britain, you have to look back to World War One and the Spanish flu to find another two year period so deadly.

Now, newly released documents show that in the earliest days of the pandemic, top scientists feared Covid had leaked from a labWuhan is home to the Wuhan Institute of Virology, which studies bat coronaviruses.  in China.

In early February 2020, British scientist Sir Jeremy FarrarFarrar is director of the Wellcome Trust, a global charitable foundation which helps to solve health challenges.  emailed Dr Anthony Fauci, the US President's Chief Medical Advisor. He warned that the evolution of a SARS-like virus inside human tissue in a low-security lab may have "accidentally created a virus primed for rapid transmission between humans".

"I just can't figure out how this gets accomplished in nature," added one American virologist.

So why are we only hearing about this now? The theory was controversial. China is a powerful nation. It is also a major source of funding for scientific research. One Dutch professor warned that accusing the country could do "unnecessary harm to science".

In 2020, many people dismissed the lab leak idea. Now, some scientists are taking it seriously once again.

"I think the lab origin is more likely than not," Harvard scientist Dr Alina Chan told British MPsMembers of Parliament. MPs are elected to represent people in 650 different geographical areas.  in December. "Right now it's not safe for people who know about the origin of the pandemic to come forward."

But not everyone agrees. Diseases like SARS and MERS jumped from animals to humans. And the World Health Organisation has declared a lab leak highly unlikely.

China have responded to lab leak claims by pushing their own conspiracy theories. They claimed the virus was brought into China by the US military.

Most scientists agree this is fake news. But as for the other theory, nobody is sure yet.

One thing is clear: if scientists prove that Covid did not evolve naturally, the fallout will be huge. It could not only change how we study viruses - it could alter how the world sees China for decades to come.

Yes: The evidence is building up. After two years of searching, no animal host for the virus has been found. Beijing's refusal to work with investigators is proof they may have something to hide. 

No: We should not underestimate the power of nature. Deadly pandemics have brought the world to its knees before, with no human intervention. Covid-19 evolved naturally too. 

Or...? We will likely never know for sure how the virus first appeared in Wuhan. To blame a group or country is divisive. It will not help us prepare for future pandemics.