The government is expected to revise its list of "Test & Go" countries following the spread of the Omicron variant of Covid-19.

The Centre for Covid-19 Situation Administration (CCSA) said the list of low-risk countries eligible for the tourism opening scheme will be reviewed and Covid-19 screening measures will be intensified.

The CCSA's operation centre will identify "high-risk" countries before holding a meeting on Friday to decide on the extent to which the "Test & Go" scheme may need to be revised or suspended completely.

"We're monitoring the spread of Omicron in other countries, not just the UK. The situation is alarming and we must take necessary precautions," a CCSA chief said.

The entry programme, which started in November, applies to fully vaccinated visitors from specific countries.

The Department of Disease Control on Monday confirmed the local transmission of the Omicron variant.

A 49-year-old-Thai woman contracted the virus from her husband, a Colombian pilot who arrived from Nigeria and entered the country via the sandbox programme on Nov 26.

The man, who had received two shots of the AstraZeneca vaccine prior to entry, tested negative for Covid-19 upon arrival and received a booster shot of the Pfizer vaccine on Dec 1.

However, he spent the 4th to the 6th of December suffering from a fever, tiredness and a sore throat. His antigen test was negative.

On Dec 7 he was taken to hospital where the RT-PCR test came back positive.

On Dec 10 both he and his wife were confirmed to have contracted the variant. His wife's Omicron infection was later confirmed as the country's earliest recorded case.

"To slow the spread of Omicron we need to do three things -- slow the arrival rate, especially under "Test & Go", speed up vaccinations and wear masks," a department member said.

As of Dec 19, there were 63 confirmed Omicron cases.

Of arrivals who tested positive for Covid-19, about 25% were found to be infected with the Omicron variant.