Two people who recently arrived in Thailand from abroad tested positive for Omicron's immune-evasive XBB sub-variant, according to the Department of Medical Science.
The XBB sub-variant is among several new variants in Thailand, doctors said.
Department director-general Supakit Sirilak said on Monday that even though the country has fully reopened and travel curbs eased, the department is still monitoring and updating information on Covid-19 sub-variants.
The department has examined 128 samples of various Omicron subvariants, and 126 of them are still BA.4 and BA.5 while only two BA.2 samples were detected. BA.2.75 has not been detected, Dr Supakit said.
The World Health Organisation (WHO) is also monitoring the situation and has so far found no additional variants of concern, with Omicron remaining the dominant variant, he said.
However, the WHO has urged countries around the world to monitor multiple sub-lineages of the Omicron variant such as BA.5, and BA.2.75 as well as the XBB sub-lineage which is a recombinant variant of two highly transmissible and immune evasive sub-lineages BM.1.1.1 and BJ.1, Dr Supakit said.
According to the Global Initiative on Sharing Avian Influenza Data (Gisaid), an international genomic database, Thailand has 19 cases of BA.2.75 and 11 cases of its subvariants of BA.2.75.1, BA.2.75.2, BA.2.75.3 and BA.2.75.5.
Dr Supakit further said that two cases of XBB sub-lineage were detected last month in two people: a foreign woman, 60, who arrived from Hong Kong and a Thai woman, 49, who returned from Singapore.
The 60-year-old had an examination at a hospital and tested positive. She had mild symptoms and self-isolated at a hotel. The 49-year-old also had an examination at the same hospital and tested positive. She also had mild symptoms but self-isolated at home. Both cases have already recovered, Dr Supakit said.
"Don't panic about the XBB sub-lineage. There is no proof that it causes severe conditions," he said.
"In Singapore where the XBB is now the predominant subvariant, the number of patients with severe symptoms is only proportionate to the rising number of infections. The strain itself has not caused more severe disease than previous variants," he said.
He said the latest Omicron subvariant BF.7 was detected in two patients in Thailand.
One is a 16-year-old foreigner living in Bangkok, and the other is a 62-year-old woman who works as a medical professional. Both cases don't have severe symptoms, he added.
The BF.7 subvariant was first detected in northwest China's Inner Mongolia Autonomous Region, and it is fast spreading and has already been detected in several other countries including the United States, the UK, Australia and Belgium.
Ten cases of the BN.1 subvariant were also detected in Thailand, Dr Supakit said, adding that the BQ.1.1 Omicron subvariant has not been found yet, he said.
Dr Supakit said while sub-lineages of Omicron are highly transmissible, they do not cause severe symptoms and general precautions such as the wearing of masks in crowded places, and hand-washing are still recommended while people in high-risk groups are advised to receive booster shots of Covid-19 vaccines.
Jakkarat Pittayawong-anont, director of the Department of Disease Control's epidemiology division, said on Monday that the number of new Covid-19 cases of coronavirus, people with severe conditions and patients dependent on ventilators, and related fatalities continue to decline.
Between Oct 9-15, a total of 53 fatalities, mostly from the high-risk "608" group and unvaccinated people, were recorded, Dr Jakkarat said. Hospital bed occupancy rates stood at 4.9%, and there were about 2,200 patients.
With an influx of foreign tourists, the number of inpatients is expected to rise, though the fatality rate will be low as the Covid-19 infection situation is now similar to seasonal influenza, Dr Jakkarat said.
Health officials have not been complacent and are still maintaining surveillance of new variants and monitoring people arriving from abroad, he said.
