Why we might never know the source of Covid-19

The accepted understanding from the beginning of this outbreak was that the Huanan Market in Wuhan is where Covid-19 originated. Credit: AP

China banned the sale of dog meat on Friday, declaring that such animals were for companionship, not for consumption.

So, yes. The country does have a problem.

The Government does need to make the ban on its wildlife markets permanent.

• Wuhan residents emerge as coronavirus lockdown ends
• Coronavirus: The Wuhan market where the pandemic started

The accepted understanding from the beginning of this outbreak was that the Huanan Market in Wuhan is where Covid-19 originated.

Why else would the Government shut it down?

And why else would a cluster of infections among its workers be reported as the first known cases?

A lot of the evidence from the market was destroyed during multiple rounds of disinfecting. Credit: AP

The reality is that a definitive link between the market and Covid-19 may never be established. An exact source may never be confirmed.

A study of 41 of the first novel coronavirus patients found only 27 out of 41 had direct exposure to the market. And one of the first reported cases also had no link.

Huanan is one of thousands of wet markets across China where meat and seafood stalls trade side by side with stores selling snakes, bamboo rats, a whole array of other animals and yes, bats.

Such markets have long been linked to coronavirus outbreaks. Experts have told us there are several small coronavirus outbreaks a year in China but usually they are locally contained.

Police stand guard outside Wuhan Huanan Wholesale Seafood Market. Credit: AP

Therefore, as Covid-19 took hold it was supposed that this had also come from an animal source. The SARS outbreak of 2002-3 was traced back to bats and moved into civet cats before being passed on to humans.

The working assumption was that this new, and related coronavirus, had similar origins.

Bats were soon cited as the most likely first host, and pangolins as the intermediary host.

Subsequent studies have both supported and questioned those conclusions, so there is still no decisive evidence.

A definitive link between the market and Covid-19 may never be established. Credit: AP

Efforts to pinpoint the source have also been hampered by the fact much evidence from the market was destroyed during multiple rounds of disinfecting.

All we know for sure is that several people from the market were infected and they were among the first reported cases.

And given what we know about SARS, it appears logical to suppose bats or reptiles were the origin.

The closer scientist can get to establishing the facts - precisely what, when and how this outbreak began - the more information they will have to help stop this pandemic, and prevent the next one.