Entry requirements concerning Covid-19 for international passengers 
      COVID-19, formerly classed as a “dangerous communicable disease” has been downgraded to a “communicable disease that requires surveillance,” causing people who travel to Thailand to question whether they have to comply with any announcements or rules.

      The Civil Aviation Authority of Thailand (CAAT) issued a Notification of Air Operators (NOTAM) informing airlines and relevant aviation sectors around the world about Thailand's public health measures for people traveling to the Kingdom.

• International passengers are not required to provide information on obtaining a vaccine or a letter from a doctor certifying that the recovery from COVID-19 has not been more than 6 months.
• Inbound passengers returning to a country that requires a negative RT-PCR test result must have at least USD 10,000 of health insurance covering COVID-19 treatment in case of infection and positive test, which may mean staying in Thailand 7 more days.
• Mission personnel, cabin crew, and students, may use a certificate from the host agency or other form of proof of insurance.
• Passengers holding Thai passports and passengers transferring or on-going are exempt from health insurance document verification. The airline will adhere to the relevant requirements and follow the guidelines as appropriate, such as asking passengers to wear masks throughout the flight, except during meal times or during emergencies. Passengers who develop symptoms of COVID-19 during their journey will be advised to undergo infection testing upon arrival at their destination.

Ref : https://www.caat.or.th/th/archives/70601

https://www.thaigov.go.th/news/contents/details/63623