Supakit Sirilak, director-general of the Department of Medical Sciences, said up to 78 per cent of foreign visitors have also tested positive for BA.4/5, while 34 per cent of patients upcountry have been infected by the subvariants.
“The BA.4/5 subvariants have started overtaking the Omicron BA.1/2 subvariants, but not too quickly,” he said.
He said 164 patients infected with BA.4/5 subvariants in Bangkok have shown mild symptoms, while 10 patients have developed severe symptoms.
In the provinces, 309 patients infected by the BA.4/5 subvariants have developed mild symptoms, while 45 are suffering severe symptoms.
“Initially we found that most patients infected with BA.4/5 subvariants developed severe symptoms, but there is not enough information,” he said.
Citing the World Health Organisation’s data, he said the global number of patients infected with Omicron BA.4 and BA.5 has risen from 11 per cent and 37 per cent to 12 per cent and 52 per cent, respectively.
He also pointed out that people who had been infected by the Omicron BA.1/2 subvariants can be infected by BA.4/5 as Japanese lab research shows that the mutation in the BA.4/5 subvariants’ spike protein allows them to escape immunity and spread quickly.
“It is clear that Omicron BA.4/5 infections in Thailand are likely to surge,” he said.
Supakit asked hospitals to submit details on patients who developed lung inflammation, had to be plugged to a respirator or succumbed to the virus, so the department can get a clearer picture.
He has also asked people to adhere to all Covid-19 prevention measures and get their booster jabs to contain the spread of Covid-19 as well as prevent the risk of developing severe symptoms or death.