He pointed out that it took Delta two to three months to replace Alpha as the dominant strain, but it took only a month for Omicron to take over from Delta.
He explained that most Omicron cases were found among foreigners in December before it spread among locals in January. He was citing a study conducted by Chulalongkorn University's Centre of Excellence in Clinical Virology.
"Omicron will become the dominant strain in Thailand this month based on the principles of evolution,” he said.
Dr Chalermchai Boonyaleephan, vice-chair of the Public Health Commission, agreed that Omicron was taking over as it has infected 97.1 per cent of patients in the country. Only 2.8 per cent have been infected with Delta, he said, citing a study conducted by Ramathibodi Hospital's Centre for Medical Genomics from January 3 to 16.
He added that the number of Omicron patients would continue to rise gradually in Thailand and hit a peak in three months before falling.
"I hope there is no new Covid-19 variant that spreads faster than Omicron in the future,” he said.