Health officials have been tracing the movements of a Myanmar mother and her child after the baby tested positive for the coronavirus disease 2019 after returning home from Thailand.
Dr Suwannachai Wattanayingcharoenchai, director-general of the Department of Disease Control, said on Wednesday that the contact tracing was underway.
Myanmar also imposed a curfew in Myawaddy town opposite Thailand's Tak province.
The two-year-old child reportedly left Mae Sot district of Tak with her mother on Sept 4. Her infection was confirmed in Myanmar on Sunday.
Dr Suwannachai said the mother and child did not pass an official border crossing and might have used any of about 50 uncontrolled natural crossings there.
Health officials collected samples from 2,635 Thai and foreigners in Mae Sot on Sept 8 and 9 and no one tested positive for Covid-19, he said.
After the investigation is done, people in contact with them will be identified and tested, Dr Suwannachai said.
