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Update of surveillance data in winter influenza season

     The Controller of the Centre for Health Protection (CHP) of the Department of Health, Dr Leung Ting-hung, today (February 11) reported the latest surveillance data of the winter influenza season and again urged the public to heighten vigilance and get vaccinated early against seasonal influenza.

     "The current influenza activity in Hong Kong remains very high. In the upcoming Lunar New Year, the public should maintain strict personal hygiene both locally and during travel. Wash or clean hands frequently, especially before touching the mouth, nose or eyes, or after touching public installations such as handrails or door knobs. Wear a mask when respiratory symptoms develop, especially when going to crowded places or attending festive gatherings. High-risk persons may wear masks against infections," Dr Leung said.

     "Surveillance so far shows that severe and fatal influenza-associated cases in adults affected the elderly most. While vaccination remains an important means to prevent influenza with a certain degree of cross-protection against different but related strains, it also reduces disease severity, particularly for high-risk persons," Dr Leung added.

Local surveillance

     Regarding severe cases, from noon yesterday (February 10) to noon today, 11 additional cases of influenza-associated admission to intensive care units or death (including six deaths) among adults aged 18 or above have been recorded under the enhanced surveillance in collaboration with public and private hospitals reactivated since January 2. This brings the total number to 247 (164 deaths) so far this year. Apart from the six deaths among newly reported cases, there was one additional death in the past 24 hours among previously reported cases requiring intensive care unit admission. Among them, 232 were A(H3N2), six were B and nine were A pending subtype. In the last winter season in early 2014, 266 (133 deaths) were filed.

     Of note, in the 247 cases and 164 deaths above, 209 cases (84.6 per cent) and 152 deaths (92.7 per cent) involved elderly persons aged 65 or above. Senior citizens yet to be vaccinated should do so promptly as vaccination can reduce disease severity, hospitalisations and deaths, particularly for high-risk groups.

     Furthermore, no additional cases of severe paediatric influenza-associated complication among children aged under 18 have been reported since yesterday via the ongoing reporting system. The total number this year hence remains at 11 (no deaths) and all were A(H3N2). In 2014, 27 (four deaths) were filed.

     Among respiratory specimens received by the CHP's Public Health Laboratory Services Branch, the percentage that tested positive for influenza viruses was 34.4 per cent in the week ending February 7. Over 95 per cent of influenza virus detections were A(H3N2).

     Regarding influenza-like illness (ILI), the number of institutional outbreaks reported to the CHP decreased from 95 (affecting 575 persons) in the week ending January 31 to 43 (208 persons) last week. As of yesterday, 24 (92 persons) had been recorded this week. The outbreaks in the past four weeks mainly occurred in primary schools (36.4 per cent), residential care homes for the elderly (31.8 per cent) and KGs or CCCs (10.1 per cent).

     In addition, the ILI consultation rates reported by both sentinel general out-patient clinics (GOPCs) and private doctors remained high. In GOPCs, the rate further rose from 10.0 ILI cases per 1 000 consultations in the week ending January 31 to 11.5 last week, while that among private doctors was 71.0 last week as compared to 61.1 in the previous week.

     The influenza-associated public hospital admission rates among children aged under 5 and the elderly aged 65 or above were respectively 3.08 and 3.76 cases per 10 000 persons last week, compared with 2.61 and 5.46 respectively in the week earlier. The rate for the elderly has remained at a high level, which is above the levels recorded in the past few years.

Situation of neighbouring and overseas areas

     Influenza activity in some overseas countries in the northern hemisphere has peaked and started to decrease while the others remained elevated. Influenza A(H3N2) virus is predominating so far.

     Influenza seasons may have passed in North America. The percentage that tested positive for influenza viruses in the United States has peaked at 31.79 per cent in the last week of 2014 and dropped to 17.5 per cent in the week ending January 31. That in Canada also peaked at 34.6 per cent and then decreased to 25.0 per cent in the same period. The number of outbreaks in long-term care facilities in Canada recorded a peak of 152 in the second week of January and then dropped to 64 in the week ending January 31.

     On the contrary, the percentage that tested positive for influenza viruses in Europe remained at a high level of 49 per cent in the week ending February 1, the same level as in the previous week, and it is over the threshold of 10 per cent. However, that in England already reached a peak of 31.7 per cent in the first week of 2015 and decreased to 18.2 per cent in the week ending February 1.

     The flu activity in Taiwan continues to increase with the percentage that tested positive for influenza viruses in Taiwan increasing to 22.5 per cent in the week ending January 24 from 21.9 per cent in the preceding one. In Japan, the average number of reported ILI cases per sentinel site was 29.11 in the week ending February 1, as compared to 39.42 in the week ending January 25.

     Locally, as of February 8, about 241 000 and 234 000 doses of seasonal influenza vaccines have been administered to eligible groups under the Government Vaccination Programme and the Vaccination Subsidy Schemes 2014/15 respectively.

     The public should maintain good personal and environmental hygiene against influenza and other respiratory illnesses:

* Receive seasonal influenza vaccination for personal protection;
* Wash hands with liquid soap and water properly whenever possibly contaminated;
* When hands are not visibly soiled, clean them with 70 to 80 per cent alcohol-based handrub;
* Cover the nose and mouth when sneezing or coughing, and wash hands thoroughly afterwards;
* Dispose of soiled tissue paper properly in a lidded rubbish bin;
* Put on a surgical mask when respiratory symptoms develop;
* Maintain good indoor ventilation;
* When influenza is prevalent, avoid going to crowded or poorly ventilated public places; high-risk individuals may consider putting on surgical masks when staying in such places; and
* Maintain a balanced diet, exercise regularly, take adequate rest, do not smoke and avoid overstress.

     The public may visit the CHP's pages below for more information:

* The influenza page (;
* The weekly Flu Express report (;
* The update on severe seasonal influenza cases (;
* The vaccination schemes page (; and
* The list of participating doctors (

Ends/Wednesday, February 11, 2015
Issued at HKT 19:35


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