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 Organisation has issued a dire warning: within eight weeks, half of Europe will have caught the OmicronAn extremely contagious variant of Covid-19 first reported in November 2021. variant.

The statistics are shocking. Today, the official worldwide death toll stands at more than 5.5 million. In Britain, you have to look back to World War One and the Spanish fluThe 1918 influenza pandemic infected an estimated 500 million people worldwide.  to find another two year period so deadly.

Now, newly released documents show that back at the start 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 emails also suggest that top scientists were concerned about offending China. It is one of the world's most powerful nations and a major source of funding for scientific research. "Further debate about such accusations would do unnecessary harm to science," warned Dutch virologist Dr Ron Fouchier.

In the months following, as Covid-19 spread from China to the world, many dismissed the idea of a lab leak as a conspiracy theory. Now, the theory is gaining traction once more.

"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 that a lab leak is the most likely explanation. Previous outbreaks, like SARSSevere Acute Respiratory Syndrome, a disease that makes it very difficult to breathe. and MERSShort for Middle East Respiratory Syndrome. Another type of coronavirus, it is also known as camel flu., jumped naturally from animals to humans. In March 2021, the first phase of a WHO investigation concluded that a zoonotic spillover event was the most likely answer.

In response to lab leak claims, officials in China have pushed conspiracy theories, claiming the virus was brought to Wuhan by US soldiers or manufactured in a US army base.

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-19 did not evolve naturally, the consequences will be huge. It could alter not only how academics study dangerous viruses, but also fundamentally change China's relationship with the world for decades to come.

Yes: The evidence is mounting. After two years of searching, no animal host has ever been found. Beijing's refusal to cooperate with investigators shows that officials may have something to hide. 

No: We should not underestimate the power of nature. Deadly pandemics have brought the world to its knees in the past - all without human interference. Covid-19 evolved naturally too. 

Or...? We will likely never know for sure how Covid-19 first appeared in Wuhan. Appointing blame is divisive and unnecessary. It will not help us to prepare for future pandemics.