We are living through one of the deadliest periods in modern history. Covid is surging. Hospital beds are filling up again. People are staying at home.

Omicron is spreading fast. In eight weeks, half of Europe will have caught the variant. 

The statistics are shocking. The virus has killed at least 5.5 million people. 

Now, newly released documents show that at the beginning of the pandemic, top scientists feared Covid-19 had leaked from a lab in China. 

In February 2020, British scientist Sir Jeremy Farrar emailed the US President's Chief Medical Advisor. He was worried that scientists may have accidentally released a virus that was very infectious to humans.

Another top scientist agreed. "I just can't figure out how this gets accomplished in nature," he said.

But the theory was controversial. China is one of the world's most powerful countries. It spends a lot of money on science. One Dutch professor warned that accusing China without proof could do "unnecessary harm to science".

In 2020, many people dismissed the lab leak idea. Now, some scientists think it could be true.

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

Not everyone agrees. Diseases have spread naturally from animals to humans in the past. An investigation by the World Health OrganisationThe United Nations agency responsible for global public health. concluded that a lab leak was "extremely unlikely". 

Chinese officials claimed US soldiers brought the virus to Wuhan. Most scientists agree: this is fake news.

If scientists prove coronavirus did leak from a lab, the fall out will be huge. It could change how humans study diseases. And China's relationship with other countries may get worse.  

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 shows they may have something to hide. 

No: We should not underestimate the power of nature. Deadly pandemics have affected millions before. 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.