In a Facebook post on Friday, Assoc Prof Dr Thira Woratanarat from Chulalongkorn University's Faculty of Medicine advised the government to hold off on fully reopening the country.
He cited comments made by Dr Takeshi Kasai, the World Health Organisation's regional director for the Western Pacific, who warned countries in Asia to get ready for the Omicron variant.
Since it was detected in South Africa on November 24, Omicron has spread quickly in many parts of the world, from Africa to Europe, North and South America, Oceania and Asia.
Thira also pointed out that many countries near Thailand like Hong Kong, Japan, India, South Korea, Singapore and Malaysia have reported Omicron cases.
The professor went on to say that all sectors, ranging from education to business, trade and service, need to adapt to the new changes, adding that there is no way everything will return to normal soon as many parties claim.
Thira also said that the administering of vaccines should be efficient and up to international standards and that the government should make RT-PCR tests free nationwide.