Lab leak or natural origin? We ask an expert to weigh up the evidence

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Last week FBI director Christopher Wray endorsed the theory that Covid-19 spread to humans as a result of a leak from a Chinese laboratory.

Mr Wray would not reveal what evidence the claim was based on, but said the FBI has “folks, agents, professionals, analysts, virologists, microbiologists etc who focus specifically on the dangers of biological threats like novel viruses like Covid.”

The lab leak theory isn’t new. Since the outbreak of the pandemic in the Chinese city of Wuhan in 2020, there has been speculation that the Wuhan Institute of Virology could have been the source of the Sars-CoV-2 virus.

The theory was broadly dismissed by the wider scientific community in the early stages of the pandemic. But Mr Wray’s recent comments have put renewed focus on the claim.

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The competing theory – that the virus jumped from bats, to an intermediate host, to humans – is still widely viewed as the most probable.

But there isn’t a consensus. The science community is divided and the reporting is often confusing and contradictory.

Today, the H5N1 virus that causes bird flu is rampant. Scientists fear it could be the next pathogen to make the jump from animals to humans.

To understand what we know about the origins of Covid-19 and the threat posed by H5N1, Aideen Finnegan talks to UCD professor of virology Dr Gerald Barry on today’s In the News podcast.