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Press Release

Latest update of surveillance data in winter influenza season

4 March 2015

The Centre for Health Protection (CHP) of the Department of Health today (March 4) 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.

"Although some surveillance data have continued to decrease for several weeks from peak levels, the overall influenza activity in Hong Kong is still at a high level and is expected to remain so for some time. We also note that the influenza activity in Macau and Taiwan remain at a high level. Continued vigilance is hence warranted," a spokesman for the CHP said.

Local surveillance

As for laboratory surveillance, among respiratory specimens received by the CHP's Public Health Laboratory Services Branch, the percentage tested positive for seasonal influenza viruses decreased from 25.2 per cent in the third week of February to 22.2 per cent last week, compared with the peak at 38.7 per cent in the last week of January. About 92 per cent of influenza virus detections were A(H3N2) while around six per cent were B.

Regarding severe cases, from noon yesterday (March 3) to noon today, nine additional cases of influenza-associated admission to intensive care units or death (including eight deaths) among adults aged 18 or above have been recorded under enhanced surveillance in collaboration with public and private hospitals reactivated since January 2, bringing the total to 439 (325 deaths) so far. Among them, 420 were A(H3N2), four were A(H1N1)pdm09, five were A pending subtype and 10 were B. In the last winter season in early 2014, 266 (133 deaths) were filed.

Last week, 71 cases (54 deaths) with a daily average of 10.1 cases (7.7 deaths) were recorded, compared with 56 cases (43 deaths) with a daily average of eight cases (6.1 deaths) in the previous week.

The CHP has issued letters to hospitals to extend the enhanced surveillance above in view of the latest situation.

Meanwhile, no additional cases of severe paediatric influenza-associated complication or death among children aged under 18 have been reported since yesterday via the ongoing reporting system, and the total this year hence remains at 17 (one death) and all were A(H3N2). In 2014, 27 cases (four deaths) were filed.

Turning to influenza-like illness (ILI), the number of institutional outbreaks reported to the CHP increased from 18 (affecting 97 persons) in the third week of February to 26 (121 persons) last week. As of yesterday, seven (38 persons) had been recorded this week. The outbreaks in the past four weeks mainly occurred in residential care homes for the elderly (55.3 per cent) and schools (33.3 per cent).

Situation of neighbouring and overseas areas

The influenza activity of neighbouring areas remained elevated while that of a number of overseas areas in the northern hemisphere has peaked and has been decreasing, with the A(H3N2) virus predominating so far.

In Macau, the percentage tested positive for H3N2 among ILI patients was 15.7 per cent as of February 26, compared with 6.1 per cent in January. The influenza season in Taiwan persisted as the percentage tested positive for influenza viruses was still at a high level of 29.9 per cent in the second week of February, compared with 41.3 per cent in the preceding one. That in Europe remained at a high level of 49 per cent in the week ending February 22, which is over the threshold of 10 per cent.

In Japan, the average number of reported ILI cases per sentinel site has been decreasing. The percentage tested positive for influenza viruses in the United States, Canada and England has also been decreasing.

Locally, as of March 1, about 251 000 doses and 242 000 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;
  • Wash or clean hands frequently, especially before touching the mouth, nose or eyes, or after touching public installations such as handrails or door knobs;
  • 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:

4 March 2015