Thailand reports first Omicron cluster

The infections stem from a couple who travelled from Belgium through the country's Test and Go scheme that waived quarantine for vaccinated arrivals, she said.

Both had tested negative for infections before travelling and after arrival in Thailand in early December.

"By December 15, they started having symptoms and tested positive and were later confirmed to have the Omicron variant," she said.

The announcement comes as Thailand's capital city Bangkok cancelled government-sponsored New Year activity, including midnight prayers

Fireworks and countdown events organised by malls were still going forward and would require proof of vaccination and antigen test results.

The health ministry also previously said it would introduce a fourth booster dose for medical personnel.

So far, Thailand has 205 infections from the Omicron variant, mostly in foreign arrivals. Of that number, 25 people were infected with the Omicron variant by those from abroad.

Other clusters are being investigated in the country's south, senior health Supakit Sirilak told a separate news briefing.

The country reported its first local transmission of the variant on Monday and later reinstated quarantine for foreign arrivals, ending a waiver for vaccinated tourists.

A sandbox program that requires travellers to stay on the resort island of Phuket for seven days remained in place.

Protective measures should be followed closely and slow the outbreak as much as possible, Supakit said.

Thailand has reported a total of 2.2 million confirmed infections and 21,528 deaths. About 62 per cent of an estimated 72 million people living in the country have received two doses of vaccinations.