New Omicron subvariants detected
More Omicron subvariants have been detected in Thailand in recent weeks, particularly the sublineage BA.2.75, first identified in India in early May, which now accounts for 42.9% of all samples tested, the Department of Medical Sciences (DMS) revealed yesterday.
The sublineage BA.2.75 made up only 23.6% of all samples tested in the department’s previous monitoring of coronavirus subvariants using the whole genome sequencing technique, said Dr Supakit Sirilak, director-general of the DMS.
As Covid-19 continues spreading, the chance of more subvariants emerging remains as the virus keeps mutating, Dr Supakit said.
Of a total of 246 samples collected from RT-PCR Covid-19 testing and whole genome sequencing from Nov 12 to 18, about 138 were found to be the BA.2.75 and its sublineages, including BA.2.75.2, BA.2.75.5.1, and BA.2.75.1.2, he said.
Other than these BA.2.75 sublineages, nine samples were found to be the BQ.1 sublineage, which has been spreading in the United States and Europe. Thirteen other samples were the XBB sublineage that is found to have spread in Singapore, Dr Supakit said.
The good news, however, is that there were no signs of increasing virulence in these mutated subvariants found despite the fact that their mutations could lead to their ability to spread and infect humans more easily, explained the DMS chief yesterday.
An important mutation in the protein spike of the BA.2.75 subvariant, known as G446S, is believed to have resulted in a significant increase in the virus’s ability to escape from neutralising antibodies, he said.
Thailand recorded its first known case of BA.2.75 in late June, Dr Supakit said.
The DMS has constantly been monitoring the Covid-19 situation and its subvariants and sharing the data obtained through this work with GISAID, a global science initiative and primary source established in 2008 that provides open access to genomic data of influenza viruses and the coronavirus responsible for the Covid-19 pandemic.
Deputy Prime Minister and Public Health Minister Anutin Charvirakul, meanwhile, has insisted that even though the existing Covid-19 vaccines may not be totally effective against newer strains, adequate inoculation using these older vaccines can still help prevent severe symptoms from developing.