Two new Omicron sub-variants, BA.4 and BA.5, still have not been detected in Thailand, Ramathibodi Hospital's Centre for Medical Genomics (CMG) says.
The centre wrote in a Facebook post on Tuesday that it was aware of World Health Organization (WHO) concerns over the new Omicron sub-variants which could be more transmittable and cause more severe symptoms.
It said the WHO is now monitoring six Omicron sub-variants: BA.1, BA.1.1, BA.2, BA.3, BA.4 and BA.5.
BA.4 and BA.5 sub-variants have a genetic code close to BA.2, with only approximately two additional mutations from BA.2: L452R, corresponding to Delta and Lambda, and F486V, which was rarely seen in previous variants. The coronavirus has constantly mutated but this occurs only on certain genetic codes, according to the CMG.
In the case of the BA.2 sub-variant, which accounts for 94% of infections globally, it is more contagious than any previous variant. However, research suggests that BA.2 is unlikely to cause symptoms as severe as Delta, Beta and Alpha.
Of the number of cases with sub-variants reported worldwide, the WHO said 83 were BA.4 cases and 37 were BA.5. However, these two Omicron sub-variants have yet to be found in Thailand.
Meanwhile, the Department of Disease Control (DDC) yesterday reiterated its call for elderly people to be vaccinated or receive boosters.
DDC director-general Opas Karnkawinpong made the call as the country was set to mark National Day for the Elderly today, adding that 78% of Covid-19 fatalities were among elderly people.
At least 53% were unvaccinated and 33% had their second dose three months ago or more, Dr Opas said.
He called on people to ensure their elderly relatives receive their next dose at local medical centres as soon as possible.
The DDC has also distributed 3 million Pfizer vaccine doses since April 11 to sub-district hospitals across the country. The doses are ready for immediate use and do not need saline added beforehand. The vaccine can be stored for more than 10 weeks, Dr Opas said.
A booster is crucial for the elderly, he said.
Two doses result in a five-fold reduction in mortality rate, while a booster provides a 31-fold reduction in mortality rate compared to those who are not vaccinated.
