Hong Kong enters its summer influenza season with another case of severe paediatric influenza A infection reported
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New case of severe paediatric influenza A infection
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The case involves a 15-year-old boy who developed a fever, sore throat, coughing and vomiting yesterday (September 8). He attended a private hospital and was admitted to its paediatric intensive care unit. His nasopharyngeal swab specimen was positive for influenza A (H3) virus upon laboratory testing. The clinical diagnosis was influenza A complicated with septic shock. He was transferred to a general ward today and is in stable condition. So far, his household contacts are asymptomatic.
The CHP investigation revealed that the boy had received the 2024/25 seasonal influenza vaccine. Five other students in his class recently developed mild influenza-like symptoms between September 5 and 6. They sought medical treatment and none of them required hospitalisation. No outbreaks have been reported in other classes at the school so far. The CHP advised the school on the necessary infection control measures to be implemented and will continue to put the school under medical surveillance.
Since last Friday (September 5), five cases of severe paediatric influenza A infection have been recorded. This marked the first occurrence of severe paediatric cases since mid-April this year. Since January this year, the CHP has recorded a cumulative total of 16 cases of severe influenza virus infections in children. Ten of them were unvaccinated in the 2024/25 season.
Influenza activity continues to rise
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After cautiously monitoring influenza trends over the past two weeks, the CHP determined that Hong Kong has entered the summer influenza season. Summer influenza seasons do not occur every year. During the decade before the COVID-19 pandemic (between 2010 and 2019), Hong Kong experienced a summer influenza season in five years. The summer influenza seasons usually occurred between July and August, and lasted for six to 18 weeks. The CHP anticipated that the local influenza activity would remain at a relatively high level in the near term.
According to preliminary surveillance data, the percentage of respiratory specimens testing positive for seasonal influenza viruses during the week of August 31 to September 6 was 6.94 per cent (provisional figure), higher than the 6.16 per cent recorded during the preceding week (August 24 to 30).
Regarding outbreaks influenza-like illness (ILI) in schools and residential care homes (RCHs), the CHP recorded 26 outbreaks during the week of August 31 to September 6, affecting a total of 259 individuals, nearly doubling from the 14 outbreaks (affecting 81 individuals) reported during the previous week (August 24 to 30). With the start of the new school term, there has been a significant increase in ILI outbreaks in schools. The number of outbreaks rose from four (affecting 25 people) in the week ending August 30 to 15 (affecting 202 people) in the week ending September 6. In the first three days of this week (September 7 to 9), 24 school outbreaks (affecting 276 people) were recorded, with four cases involving 20 to 98 people. The CHP staff have inspected these schools and advised the schools on necessary infection control measures. These included recommending that students wear masks on campus, appropriately opening windows to improve ventilation in individual activity rooms and classrooms, thoroughly cleaning and disinfecting the campus, and suspending inter-class and inter-grade activities. The CHP also advised teachers and students to check their temperature daily before returning to school. If they develop symptoms or fever, they should not go to school. The CHP will continue to put these schools and RCHs under medical surveillance.
Vaccination effectively prevents severe cases of seasonal influenza and its complications
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Vaccination has been scientifically proven to be one of the most effective ways to prevent seasonal influenza and its complications. It also reduces the risks of in-patient admission and mortality due to seasonal influenza. The Government has all along been encouraging the public to receive vaccination as early as possible, and providing free and subsidised seasonal influenza vaccines to eligible high-risk groups through various vaccination programmes. During the previous influenza season (2024/25), approximately 2.09 million doses of seasonal influenza vaccines were administered under various SIV Programmes, setting a new historical high. Severe influenza cases among adults and children decreased significantly by 20 per cent and 60 per cent respectively, compared to the influenza seasons before the COVID-19 pandemic. It is believed to be attributable to higher vaccination rates.
The DH announced yesterday (September 8) that the 2025/26 SIV Programmes would commence on September 25 to provide a free or subsidised SIV to eligible high-risk groups through various vaccination programmes. A number of new initiatives have been introduced to encourage and enable public participation, including further enhancing the SIV School Outreach Programme so that all schools may choose to use the live attenuated influenza vaccine (LAIV nasal vaccines) and "hybrid mode", i.e. schools being allowed to choose both injectable inactivated influenza vaccines (IIV) and LAIV for the same or different outreach vaccination activities. Approximately 2 300 schools (99 per cent) have joined the outreach programme. To safeguard students' health, the CHP will publish a list of schools not participating in the programme on its official website to remind parents to promptly arrange for children in those schools to receive vaccinations from family doctors.
To make vaccinations more accessible, the Government will open all 29 of the DH's Maternal and Child Health Centres (MCHCs) for all children aged 6 months to under 2 years. Moreover, the 25 District Health Centres and District Health Centre Expresses and their service outlets under the Primary Healthcare Commission, and 74 general outpatient clinics and 38 public hospitals of the Hospital Authority to provide more choices for the public. For a list of vaccination venues, please refer to the CHP's Vaccination Schemes page. Starting from 9am on September 22, parents of eligible children may book an appointment for their children to receive vaccinations at designated MCHCs via the online booking system.
The CHP reminded high-risk persons to wear surgical masks when visiting public places. The general public should also wear a surgical mask when taking public transport or staying in crowded places. People with respiratory symptoms, even if mild, should wear a surgical mask and seek medical advice promptly, and consider whether to go to work or school. For the latest information on seasonal influenza, members of the public can visit the CHP's seasonal influenza and COVID-19 & Flu Express webpages.
Ends/Tuesday, September 9, 2025
Issued at HKT 21:26
Issued at HKT 21:26
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