Coronavirus Asia

Future pandemic could stem from coronavirus transmitted from humans to bats

A new Sars-CoV-3 virus may emerge in the future, arising from humans transmitting the coronavirus back to bats.

Known as reverse-zoonosis, this occurs when infectious viruses are transmitted from humans back to animals, said Professor Wang Linfa from the Duke-NUS Emerging Infectious Diseases programme.

He was speaking about the science behind pandemics and what could lead to a future pandemic at the Special Ministerial Conference for Asean Digital Public Health yesterday.

Prof Wang said that most scientists believe that the ancestral strain of the Sars-CoV-2 virus that causes Covid-19 exists in bats found in Asia. The virus was then transmitted to an "animal X", possibly pangolins or civets, before being transmitted to humans at the Wuhan fish market in China.

"It would be worrying if humans can infect novel hosts, like bats in the American continent, which are not natural reservoirs for the virus," he said.

A possible scenario of this would be an infected human leaving behind a half-eaten fruit, which is picked up by a bat. This research theory comes on the back of Prof Wang's expertise on bat zoonology and immunology.

"Bats have a very unique immune system in that they can sustain a virus without developing disease. However, the virus can still mutate and transmit to animal X, Y, or Z. So when that mutated virus goes to animal X,Y,Z and gets to a human, then that's where we get our disease X,Y,Z or Sars-CoV-3," said Prof Wang.

Each time a virus jumps between species, it is forced to make major changes because genetically, it has to adapt to its new host.

So, how can countries prepare for such a pandemic? Prof Wang suggests three levels of preparedness.

To pre-empt a pandemic, scientists will need to work with government agencies and international funding bodies to determine the risk of a particular virus circling in animals - especially ones that humans trade and consume most frequently - jumping to humans. Countermeasures to prevent virus spread can then be prepared.

Next, early warning signs of a new virus, such as severe, unusual cases in the intensive care unit or local clinics, should be looked out for.

When the virus has started to spread, the last resort would be to develop vaccines and therapeutics. The Duke-NUS team is working on just that - developing a booster jab to offer a broader spectrum of protection for future Sars-Cov-2 variants and other coronaviruses.

This comes after his team had found that people who both recovered from severe acute respiratory syndrome (Sars) in 2003 and who received the Pfizer-BioNTech vaccine for Covid-19 are able to produce antibodies to neutralise all known Covid-19 variants of concern, such as the Delta variant.

The antibodies could possibly also tackle other potential animal coronaviruses.

He also intends to recruit more recovered Sars patients from other places such as Hong Kong, Guangzhou and possibly Toronto.

The researchers aim to understand the level of immunity that they are able to develop from being jabbed with a range of other vaccines such as Moderna, Sinovac or AstraZeneca.

Cheryl Tan

A version of this article appeared in the print edition of The Straits Times on October 07, 2021, with the headline 'Future pandemic could stem from coronavirus transmitted from humans to bats'. Subscribe