The doctor posted on his Facebook page that he was sitting near Samut Sakhon Governor Verasak Vichitsangsri, who has since tested positive for the coronavirus.
Yong is now undergoing self-quarantine for 14 days after the meeting in Samut Sakhon province.
He urged the public to strictly follow preventive measures by wearing face masks, social distancing in public places and regularly sanitising one’s hands to stop the chain of infections.
Yong previously requested that all New Year parties be banned before the coronavirus spirals out of control.