The Civil Aviation Authority of Thailand (CAAT) said in a statement on Saturday that starting early Monday, all foreign arrivals starting early on Monday must prove they are vaccinated or provide a letter certifying that they have recovered from COVID within six months.

Unvaccinated travelers must show a medical certificate explaining why they have not received the vaccine.

CAAT said airlines would be responsible for checking documents before passengers board and has released a list of how many doses are required for various types of COVID-19 vaccines on its website.

The new measure will remain in effect at least until the end of January, CAAT said.

The vaccination requirement was scrapped by Thailand last October but has been revived as China reopens its border following the easing of its zero-COVID policy.

The first commercial flight from China to Thailand, Xiamen Airlines flight MF833, will arrive to Bangkok from Xiamen on Monday carrying 286 passengers, government spokeswoman Traisuree Taisaranakul said on Sunday.

Foreigners traveling to Thailand from a country where a negative reverse transcription polymerase chain reaction (RT-PCR) test result is a condition for entry are required to show proof of health insurance that covers COVID-19 treatment, the Health Ministry said.

The new entry requirements do not apply to Thai passport holders or passengers transiting through Thailand.