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Update of surveillance data in winter influenza season

     The Centre for Health Protection (CHP) of the Department of Health today (January 28) 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.

     "As the influenza activity of the northern hemisphere including Hong Kong remains high, in view of 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," a spokesman for the CHP 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," the spokesman added.

Local surveillance

     Among respiratory specimens received by the CHP's Public Health Laboratory Services Branch, the percentage that tested positive for influenza viruses increased from 29.42 per cent in the week ending January 17 to 30.96 per cent last week. Over 95 per cent of influenza virus detections were A(H3N2).

     Regarding influenza-like illness (ILI), in the same period, the number of institutional outbreaks reported to the CHP also rose from 41 (affecting 291 persons) in the week ending January 17 to 55 (318 persons) last week. As of yesterday (January 27), 52 outbreaks (259 persons) had already been recorded this week. The outbreaks in the past four weeks mainly occurred in primary schools (34 per cent), residential care homes for the elderly (29 per cent) and kindergartens or child care centres (14 per cent).

     In addition, the ILI consultation rates reported by both sentinel general out-patient clinics (GOPCs) and private doctors increased. In GOPCs, the rate rose from 7.2 ILI cases per 1 000 consultations in the week ending January 17 to 9.4 last week, while that among private doctors rose from 57.9 to 69.4 accordingly.

     Turning to severe cases, as of noon today, 122 cases of influenza-associated admission to intensive care units or death (including 64 deaths) among adults aged 18 or above had been recorded under the enhanced surveillance in collaboration with public and private hospitals reactivated since January 2. Among them, 115 were A(H3N2), four were B and three were A pending subtype. In the last winter season in early 2014, 266 cases (133 deaths) were filed.

     "Of note, in the 122 cases and 64 deaths above, 97 cases (79.5 per cent) and 56 deaths (87.5 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," the spokesman said.

     To date, nine cases of severe paediatric influenza-associated complication (no deaths) among children aged under 18 have been reported this year via the ongoing reporting system and all were A(H3N2). In 2014, 27 cases (four deaths) were filed.

Situation of neighbouring and overseas areas

     The influenza activity in neighbouring and overseas areas in the northern hemisphere has remained high with the A(H3N2) virus predominating so far.

     The percentage that tested positive for influenza viruses in Taiwan increased to 14.5 per cent in the first week of 2015 from 10.0 per cent in the preceding one. In Japan, the average number of reported ILI cases per sentinel site rose from 3.49 in the first week of last December to 37.0 in the week ending January 18, far higher than the baseline level of 1.00.

     In addition, the percentage that tested positive for influenza viruses in Europe continued to increase from 28 per cent in the week ending January 11 to 40 per cent in the next, which is over the threshold of 10 per cent. That in England reached a peak of 31.7 per cent in the first week of 2015 and decreased to 19.4 per cent in the week ending January 18.

     According to the World Health Organization, the influenza activity might have peaked in the United States as the percentage that tested positive for influenza viruses stood at 31.4 per cent in the last week of 2014 and dropped to 19.5 per cent in the week ending January 17. That in Canada also peaked at 34.6 per cent and then decreased to 29.5 per cent in the same period. Canada recorded 118 outbreaks of influenza A in long-term care facilities in the week ending January 17, compared with 125 in the previous week.

     Locally, as of January 25, about 225 000 and 218 000 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 vaccination schemes page (; and
* The list of participating doctors (

Ends/Wednesday, January 28, 2015
Issued at HKT 18:04


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