Hong Kong health authorities are urgently appealing to parents and schools to prioritize seasonal influenza vaccination following the confirmation of a severe pediatric flu case. The Centre for Health Protection (CHP) confirmed that an 11-year-old boy from ESF Island School is hospitalized in serious condition with a diagnosis of influenza A complicated by shock, underscoring the ongoing threat of the respiratory virus even as the summer flu season shows signs of abating.
The case, which brings the total number of severe pediatric flu infections this season to 18 (including one fatality), highlights the critical need for timely immunization, particularly among school-age children.
Cluster Identified After School Camp
The severe case involves a student who developed symptoms on November 7, days after attending a school camp from November 3 to 7. His condition worsened significantly by November 10, leading to hospital admission where he tested positive for Influenza A. Notably, the child had not received the 2025/26 seasonal flu vaccine.
The CHP has confirmed a cluster of associated infections; preliminary investigations revealed that seven of the boy’s classmates who attended the same camp tested positive for influenza A via rapid tests. Fortunately, these nine related cases were mild and did not require hospitalization. In response, CHP staff inspected the school, offered guidance on infection control measures, and initiated medical surveillance on the campus to curb further transmission.
Vaccine Protects Despite Viral Drift
Dr. Edwin Tsui, Controller of the CHP, emphasized that while the current flu season—which began later than usual—is ongoing, the seasonal vaccine remains robustly effective, even in the face of detected genetic mutations, or antigenic drift, in circulating Influenza A (H3N2) strains.
“Seasonal influenza viruses routinely undergo genetic changes, which is expected and continuously monitored by global public health bodies,” Dr. Tsui explained. He assured the public that the current vaccine is designed to offer cross-protection against related strains.
Citing recent data from the UK Health Security Agency, which indicates that H3N2 accounts for over 80% of confirmed cases in some regions, Dr. Tsui noted the significant protective benefits of the vaccine. Data suggests the seasonal shot retains approximately 75% effectiveness against hospitalization in children aged two to 17, and about 40% protection in adults.
Actionable Steps for Community Health
Vaccination is the cornerstone of public health defense against influenza. It significantly reduces the risk of severe disease, complications, and death, particularly among vulnerable populations.
Who should get vaccinated immediately?
- Everyone aged six months and older (unless medically contra-indicated).
- High-risk groups, including the elderly, young children, and individuals with chronic illnesses or immunosuppression, should prioritize vaccination.
The CHP stressed that protection develops about two weeks after inoculation. Of the severe cases reported since the vaccine program launched, only one patient had received the shot, but the onset of illness followed too quickly for immunity to take effect.
The Department of Health is actively encouraging uptake through various channels, including government subsidy schemes and private family doctors.
Addressing Uptake and Future Outlook
Flu activity began declining in late October, aligning with a marked decrease in school-reported outbreaks—from 169 in mid-October to 61 in the past week. This promising shift coincides with high participation in school outreach programs. Approximately 1,700 schools have hosted vaccination sessions since the term began, and over 96% of schools are scheduled to complete their outreach programs by the end of November.
Despite the current easing of the summer wave, Dr. Tsui cautioned that flu activity remains elevated and may fluctuate as temperatures drop. Historically, Hong Kong’s dominant winter flu season runs from January to March, and a resurgence early next year remains a distinct possibility. The CHP continues to appeal for concerted community efforts to boost vaccination rates among young children now to strengthen overall population immunity ahead of the winter months.