The Centre for Medical Genomics at Thailand’s Ramathibodi Hospital is closely monitoring a new sub-variant of the COVID-19 Omicron variant, BA.4.6, which spreads faster than others, including BA.4 and BA.5, although it has not been detected in Thailand yet.

The centre said that BA.4.6 has been classified by the US Centres for Disease Control and Prevention (CDC) as a variant of concern, after it was discovered that it has spread quickly in the states of Iowa, Kansas, Missouri and Nebraska and is now accounting for 4.1% of COVID-19 infections, according to the information available as of July 30^th.

It also said that genomic sequencing has been conducted on 5,681 samples of the BA.4.6 sub-variant in the past three months and the findings have been uploaded to the database of the Global Initiative on Sharing Avian Influenza Data (GISAID).

The BA.4.6 sub-variant is similar to BA.4, except that the Spike R346T mutation is different.

The centre said, however, that it has not concluded yet whether the new sub-variant is more serious or more capable than the others at evading immunity, or whether it is resistant to the first generation of COVID-19 vaccines, or the second generation of vaccines to be used for inoculations around the end of this year.

According to the centre, BA.4.6 is 15% more transmissible than BA.5 worldwide and 28% more transmissible than BA.5 in Asia.

It is also 12% more transmissible than BA.2.75 worldwide and 53% more transmissible than the BA.2.75 sub-variant in Asia. The BA.2.75 sub-variant, which was first diagnosed in India and has since spread worldwide, is now on a steady decline, according to the centre.

Most new COVID-19 cases in Thailand are Omicron BA.4 and BA.5.