Four new sub-variants of the Delta strain of the novel coronavirus have been found in samples analysed by Ramathibodi Hospital.
The head of the hospital's Centre for Medical Genomics, Wasun Chatratita, said the sub-variants were detected in samples sent to the centre from several hospitals across Thailand.
Prof Dr Wasun said sub-variant AY.4 (B.1.617.2.4) was found in 3% of samples sent in from Pathum Thani, while AY.6 (B.1.617.2.6) was detected in 1% of samples from all over the country.
Meanwhile, sub-variants AY.10 (B.1.617.2.10) and AY.12 AY.12 (B.1.617.2.15) were found in 1% of samples sent in from Bangkok, he said.
To date, experts have identified over 60 possible mutations to the genetic make-up of the Delta strain. Of these, 22 are known to be responsible for the emergence of new sub-variants.
The first Delta sub-variants which have been verified, AY.1 and AY.2, were first discovered in Nepal.
Separately, the spokesman for the Centre for Covid-19 Situation Administration (CCSA), Taweesilp Visanuyothin, said Bangkok reported 3,472 new cases and 79 deaths on Monday.
He also said infection rates in construction camps have been trending upwards since June 16.
According to the latest figures from the Bangkok Metropolitan Administration (BMA), 2,513 cases were found in hospitals, 176 were detected among migrant workers, while 792 were found during active case finding.
Meanwhile, 2,974 patients left the capital region to seek Covid-19 treatment in their home provinces on Sunday, down from 5,182 on Aug 11.
In total, 173,599 people have opted to receive treatment in their home provinces, according to the BMA.
Separately, permanent secretary for public health, Kiattiphum Wongrajit, stressed the government never prohibited the private sector from importing Covid-19 vaccines.
He said private companies must seek the appropriate import permit and register the vaccine with the relevant authorities because they will be held responsible for the vaccine's quality and safety.
Private companies can register the vaccine they wish to bring in with the Food and Drug Administration, which will review the vaccine's quality and side effects within 30 days.
