An influenza outbreak has killed at least nine people and left thousands sick across Thailand, according to the Southeast Asian country's health ministry.

The country has recorded at least 107,507 flu infections so far in 2025 with the number of patients increasing by about 15,000 per week, Jurai Wongsawat, a spokeswoman for the Department of Disease Control, said.

The health ministry has been speeding up the supply of vaccines for the vulnerable populations of children and the elderly.

The highest number of infections have been found among children aged five to nine followed by those under four and between 10 and 14 years old. The most common strain of the influenza virus is A/H1N1, according to the ministry.

While only around 7,800 cases of influenza were recorded across Thailand in the whole of January, the number had leapt to 99,057 by 15 February, with nine fatalities.

The youngest victim was 11 years old and the oldest 86, the health ministry said, adding that all of them had been vaccinated against the flu.

Phuket, Bangkok, Chiang Mai, Phayao, Lamphun, and Lampang are among the worst-affected provinces in the country. The highest rates of infection have been reported in schools, prisons and military camps, The Nation reported.

Dr Jurai said that there has been a steady increase in influenza cases in the country since the relaxation of the Covid pandemic restrictions. "Statistics show that the flu is spreading rapidly among children. It's recommended that schools enforce strict measures to curb infections."

To prevent further spread, infected people should stay home for at least three to five days, she said.

Yong Poovorawan, a virologist at the Chulalongkorn University Faculty of Medicine, said in an advisory: "Influenza is seasonal. It spreads in the cold season in the northern and southern hemispheres."