[LINK] Bat Signal - The hunt for the origins of SARS-CoV-2 will look beyond China

[Kim Holburn]

https://www.economist.com/science-and-technology/2020/07/22/the-hunt-for-the-origins-of-sars-cov-2-will-look-beyond-china


> The virus may have been born in South-East Asia

> ONE OF THE great questions of the past six months is where SARS-CoV-2, the virus that causes covid-19, came from. It is thought the answer involves bats, because they harbour a variety of SARS-like viruses. Yunnan, one of China’s southernmost provinces, has drawn the attention of virus hunters, as the closest-known relatives of SARS-CoV-2 are found there. But some think the origins of the virus are not to be found in China at all, but rather just across the border in Myanmar, Laos or Vietnam.
> 
> This is the hunch of Peter Daszak, head of EcoHealth Alliance, an organisation which researches animals that harbour diseases that move into people. Since the outbreak, in 2003, of the original SARS (now known as SARS-CoV), scientists have paid close attention to coronaviruses. Dr Daszak says that around 16,000 bats have been sampled and around 100 new SARS-like viruses discovered. In particular, some bats found in China are now known to harbour coronaviruses that seem pre-adapted to infect people. The chiropteran hosts of these viruses have versions of a protein called ACE2 that closely resemble the equivalent in people. This molecule is used by SARS-like viruses as a point of entry into a cell.

....

> Support for the idea that something resembling SARS-CoV-2 might have been circulating in the region before the pandemic began also comes from another intriguing observation: the low incidence of covid-19 in South-East Asia, particularly in Vietnam. John Bell, a professor of medicine at the University of Oxford, says everyone thought there would be a flood of cases in Vietnam because the country is right across the border from China. Yet Vietnam has reported only 300 in a population of 100m, and no deaths. The country did not have a great lockdown either, he adds. Nobody could work out what was going on.
> 
> One explanation, he suggests, is that Vietnam’s population is not as immunologically “naive” as has been assumed. The circulation of other SARS-like viruses could have conferred a generalised immunity to such pathogens. So, if a new one emerged in the region, it was able to take hold in the human population only when it travelled all the way to central China—where people did not have this natural resistance.


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Kim Holburn
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