The origins of the virus that killed almost 750,000 people worldwide are still mostly unknown.
Researchers in Thailand have taken to the countryside to catch bats in their caves in an effort to study them and trace the origins of coronavirus.
So far, the closest match has been found in the horseshoe bat species populating the south-western Chinese province of Yunnan.
Thailand has 19 species of such bats - but none had been tested for coronavirus.
The researchers hiked up a hill in the Sai Yok National Park, in the western province of Kanchanaburi, and set up nets to trap some 200 animals.
The team, from the Thai Red Cross Emerging Infectious Diseases-Health Science Center, took saliva, blood and stool samples from the bats before releasing them.
They also took samples from other species to better understand the pathogens carried by them.
Bats remain the number one suspects for the initial transmission of coronavirus.
Scientists believe they carried a similar virus for decades, and that the new coronavirus might have emerged from contact between different species.
"What we do know is that there are lots of related coronaviruses that are found in bats, and the more we sample bats, the more we find that they carry coronaviruses," French epidemiologist Dominique Pontier told Euronews.
Chinese researchers agree bats may be the COVID-19 original hosts of the virus, and also pointed out that pangolins are likely to be "intermediate hosts".