It was New Year’s Eve. The ProMED reporting program, under auspice of ISID, reported on a pneumonia outbreak of unknown origin in Wuhan. Thailand received 8 direct flights from Wuhan daily at its 4 international airports. By January 3, 2020, Thailand’s Department of Disease Control had several protocols and screening measures in place at the international airports, specifically targeting flights from Wuhan. Specimens were collected from travelers with fever and/or cough (Patients Under Investigations (PUI)) and sent to the Thai Red Cross Emerging Infectious Diseases Health Science Centre (TRC-EID), the first PACS site in Thailand (implemented since 2015), and the National Institute of Health, Department of Disease Control, Ministry of Public Health (NIH-DMSc, PACS site since Dec 2019). On January 8, 2020, sample from a PUI was sent to TRC-EID and NIH-DMSc. Both laboratories worked tirelessly to narrow down and identify the novel pathogen. The novel pathogen was sequenced by January 10th, when China publicly released the sequence of nCoV-2019 (now known as SARS-CoV-2). The laboratories compared their obtained sequence with the sequence from Wuhan, which shared 100% identity. Thailand officially announced the first case of COVID-19 on January 11, 2020 detected outside of China.
You can read more about it here: https://www.who.int/thailand/news/feature-stories/detail/bat-research-and-lab-readiness-boost-thailand-s-campaign-against-the-novel-coronavirus