Strain known as A H3B2 is more vaccine resistant but not more severe than other variants
PUBLISHED : 8 Jan 2026 at 14:53
A girl reacts to being given a flu jab at Wat Pracha Rabuetham School in Dusit district of Bangkok, in May last year. (Photo: Chanat Katanyu)
Well-known virologist Yong Poovorawan has warned that a mutating influenza strain A H3N2 is spreading in Thailand. It is more resistant to vaccines but does not increase in severity.
Prof Dr Yong, who heads the Center of Excellence in Clinical Virology at Chulalongkorn University wrote on his Facebook page on Thursday that influenza was spreading widely and A H3B2 raised concerns because the mutation proved to seriously reduce the efficacy of existing vaccines.
The Ministry of Public Health recorded an all-time high numb…
Strain known as A H3B2 is more vaccine resistant but not more severe than other variants
PUBLISHED : 8 Jan 2026 at 14:53
A girl reacts to being given a flu jab at Wat Pracha Rabuetham School in Dusit district of Bangkok, in May last year. (Photo: Chanat Katanyu)
Well-known virologist Yong Poovorawan has warned that a mutating influenza strain A H3N2 is spreading in Thailand. It is more resistant to vaccines but does not increase in severity.
Prof Dr Yong, who heads the Center of Excellence in Clinical Virology at Chulalongkorn University wrote on his Facebook page on Thursday that influenza was spreading widely and A H3B2 raised concerns because the mutation proved to seriously reduce the efficacy of existing vaccines.
The Ministry of Public Health recorded an all-time high number of influenza patients last year, he said. The outbreak early last year resulted from the A H1N1 2009 strain, but A H3N2 emerged late last year and continues to spread.
The A H3N2 strain has been spreading widely throughout the northern hemisphere in the cold season, he said, and its resistance to vaccines means there is a larger number of patients than usual.
The ministry’s Department of Disease Control recorded 1.09 million influenza cases from Jan 1 to Dec 6, 2025.
However, Prof Dr Yong wrote, although the mutation spurred transmission, the severity of the disease did not rise and the efficacy of antiviral medicines did not decline.
The virologist still recommends that people be vaccinated, saying the available vaccines are safe because they are inactivated vaccines. They are not expensive and have few side effects, he added.
Prof Dr Yong Poovorawan (right) administers a Covid jab to then Public Health Minister Anutin Charnvirakul at the Bamrasnaradura Infectious Diseases Institute in Nonthaburi on Feb 28, 2021. (Photo: Government House)