An infectious diseases expert on Monday said the summer flu seasonal outbreaks that started in September were mainly driven by cases in schools and would run its course in the coming one to two weeks.

Speaking on an RTHK programme, Lau Yu-lung, chairman of the scientific committee on vaccine preventable diseases at the Centre for Health Protection, said the number of outbreaks this season, including at schools and care homes, stood at around 1,220, compared to about 390 in the same period in 2023-24.

"The summer flu season this time is driven by schools, including primary schools, secondary schools as well as kindergartens," he said.

"The outbreak occurred about two to three weeks earlier before the start of the government's flu vaccination plan.

"Looking back at the data and graphs from the Centre for Health Protection, we can see that those who were hospitalised due to flu are mainly aged five years old or under, and the number of primary school and secondary school students who had been hospitalised were higher than those who were 65 or above."

When asked whether school-based jabs programmes should start earlier to better prevent outbreaks from happening on campuses, Lau said that would depend a lot on announcements regarding vaccine components by the World Health Organisation to tackle the flu strains as the virus mutates, subsequent production by drug companies worldwide, purchasing of doses by Hong Kong and the delivery time of these doses.

He also said the winter flu season had yet to start and that it was difficult to predict whether it would overlap with the summer flu season.

He called on people to get vaccinated as soon as possible, including those who had contracted influenza during the summer flu season, and wear masks when on public transport.

For her part, Polly Chan, who chairs the Aided Primary School Heads Association, said schools had strengthened measures to minimise flu outbreak risks since the Covid-19 pandemic.

This includes conducting temperature checks on a daily basis, keeping an eye out for flu symptoms in students and using 1:49 diluted household bleach to disinfect campuses.

Chan said schools would also keep tabs on student absenteeism records and notify the Centre for Health Protection if signs of a potential flu outbreak emerged.