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Hong Kong enters winter influenza season
     The Centre for Health Protection (CHP) of the Department of Health today (January 10) announced that local seasonal influenza activity has continued to increase in the past week and exceeded the baseline level, indicating that Hong Kong has entered the 2017-18 winter influenza season. The community should heighten vigilance and maintain personal protection against influenza.
     The positive percentage of seasonal influenza viruses among respiratory specimens received by the CHP increased from 9.76 per cent in the week ending December 30 to over 15 per cent in the following week. The circulating influenza viruses in the past week were predominantly influenza B, with low influenza A activity.

     In the above period, the weekly average rate of the influenza-like illness (ILI) syndrome group in the accident and emergency departments increased from 195.3 cases per 1 000 coded cases to 208.8. The overall admission rate with principal diagnosis of influenza in public hospitals increased from 0.26 per 10 000 population to 0.40.
     After the Christmas and New Year holidays, the CHP recorded an increase in institutional ILI outbreaks from two (affecting six persons) in the week ending December 30 to five (affecting 21 persons) last week. In the first three days of this week, 13 ILI outbreaks (affecting 46 persons) have been recorded. The above outbreaks occurred in primary schools (eight), residential care homes for the elderly (five), kindergartens/child care centres (five), a residential care home for the disabled (one) and a hospital (one).
     The CHP has collaborated with public hospitals under the Hospital Authority and private hospitals to monitor influenza-associated admissions to intensive care units (ICU) and deaths among patients aged 18 years or above as routine surveillance throughout the year starting in 2018. As of yesterday (January 9), 24 cases (10 deaths) had been recorded. Of note, the causes of ICU admission or death among the cases may be due to other acute medical conditions or underlying diseases. Starting tomorrow (January 11), the weekly surveillance data on adult severe influenza cases will be reported in the CHP’s Flu Express published every Thursday.

     In children aged under 18, routine surveillance of severe influenza-associated complications or deaths is ongoing. As of yesterday, one case had been recorded this year. In 2015, 2016 and 2017, 25 (one death), 31 (four deaths) and 27 (four deaths) cases were recorded respectively. Among them, 73 cases (88 per cent) did not receive seasonal influenza vaccination for the respective season.
     "We anticipate that local seasonal influenza activity will continue to rise in the coming weeks and remain at an elevated level for some time. We again urge the public, particularly children, the elderly and chronic disease patients, to observe strict personal, hand and environmental hygiene," a spokesman for the CHP said.
     The CHP will issue letters to doctors, hospitals, institutions and schools again to appeal for heightened vigilance and appropriate actions.
     "According to the latest data, the currently circulating viruses in Hong Kong, including the influenza B and influenza A H1 and H3 viruses, were antigenically similar to the components of the northern hemisphere influenza vaccine adopted in the 2017-18 Government Vaccination Programme and Vaccination Subsidy Scheme," the spokesman said. 
     "Particularly, children, the elderly and those with underlying illnesses are urged to get vaccinated as early as possible to prevent seasonal influenza as it takes about two weeks for antibodies to develop in the body after vaccination. They should promptly seek medical advice if influenza-like symptoms develop so that appropriate treatment can be initiated as early as possible to prevent potential complications. Parents and carers are reminded to render assistance in prevention, care and control for vulnerable people," the spokesman added.
     As of January 7, about 391 000 and 256 000 doses of seasonal influenza vaccines had been administered via the Government Vaccination Programme (free vaccination) and the Vaccination Subsidy Scheme (subsidised vaccination) respectively, increasing by 8.8 per cent and 2.1 per cent from the same period in the 2016-17 season.
     Globally, the 2017-18 winter influenza season has already started in most areas in the temperate zone of the northern hemisphere and the influenza activity in the United States, Canada, Japan and many countries in Europe continued to increase. In Mainland China, the overall influenza activity in both southern and northern parts continued the increasing trend. The positive percentage of influenza detections has increased to 42.8 per cent, with the predominating virus being influenza B. In Guangdong, in the week ending December 31, the proportion of ILI cases among sentinel hospitals was 6.32 per cent while the percentage of respiratory specimens tested positive for influenza was 31.98 per cent. The predominating virus was influenza B. Macao's surveillance data showed that the number of reported influenza cases in the first week of 2018 was 152, higher than 89 in the previous week.
     Besides receiving seasonal influenza vaccination as early as possible for personal protection, the public should maintain good personal and environmental hygiene for protection against influenza and other respiratory illnesses. For more information, please visit the CHP's influenza page and weekly Flu Express for more information.
Ends/Wednesday, January 10, 2018
Issued at HKT 13:01
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