A woman from Sing Buri probably caught Covid from two Thai women returning from Tachilek while they were waiting for a flight at Chiang Rai airport.
Sophon Iamsirithaworn, director of the Communicable Diseases Division, said the 51-year-old woman from Sing Buri was probably infected at Mae Fah Luang airport, not while on the plane.
The three flew from Chiang Rai to Don Mueang airport on Nok Air flight DD8717 on Nov 28. Dr Sophon rejected a theory that the virus was spread in the aircraft. All passengers wore face masks and the woman from Sing Buri sat eight rows behind the two returnees, he said.
She was probably infected in the area where the three women sat before boarding the plane. Security camera recordings showed the three women were not properly wearing their face masks.
"They were wearing their face masks below their nose and mouth," he said.
Chiang Rai is plagued by virus cases from Tachilek. The country has 38 cases linked to the spread of the virus by workers returning from the Myanmar border town, 26 of them in Chiang Rai.
Dr Sophon asked passengers on the same flights as infected women to immediately go to a hospital if they develop symptoms such as a fever, cough, runny nose, or loss of smell and taste.
Flights from Chiang Rai on the list are: Nok Air flight DD8817 on Nov 28, Thai Lion Air flight SL533 on Nov 29, WE137 of THAI Smile on Nov 29, and Thai Lion Air flight SL545 on Nov 30.
All four flights carried passengers whose tests were later positive for the virus.
