The Centre for Health Protection (CHP) of the Department of Health today (January 2) announced that local seasonal influenza activity has continued to increase in the past week and exceeded the baseline thresholds, indicating that Hong Kong has entered the 2018-19 winter influenza season. The community should heighten its vigilance for protection against influenza.
"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 get vaccinated as early as possible and observe strict personal, hand and environmental hygiene at all times," a spokesman for the CHP said.
Among the respiratory specimens received by the CHP's Public Health Laboratory Services Branch, the percentage that tested positive for seasonal influenza viruses has increased steadily since mid-November and rose to 14 per cent last week, ending December 29. The circulating influenza viruses in the past four weeks were predominately influenza A(H1) (around 80 per cent) and A(H3) (around 20 per cent), with very low influenza B activity. Of note, past epidemiological data shows that children and adults aged from 50 to 64 years were relatively more affected in seasons dominated by influenza A(H1).
The overall admission rate with principal diagnosis of influenza in public hospitals has been increasing to 0.43 per 10 000 population last week.
The weekly number of institutional influenza-like illness (ILI) outbreaks reported to the CHP ranged from eight to 17 in the past four weeks (December 2 to 29), affecting 341 persons, including 30 in kindergartens/child care centres, nine in primary schools, six in residential care homes for the elderly, four in residential care homes for persons with disabilities, two in secondary schools, and one each in a hospital and a special school.
The CHP will issue letters to doctors, hospitals, institutions and schools to appeal for heightened vigilance and appropriate actions. For schools, their management should stay alert to seasonal influenza following the end of the Christmas and New Year holiday. There may be an increase in ILI outbreaks when classes resume. As an additional measure to prevent transmission of influenza in school environments, schools are reminded to actively check the body temperature of all students every day when they arrive at school to identify those with fever. Those with fever (oral temperature over 37.5 degrees Celsius or ear temperature over 38 degrees C), with or without respiratory symptoms, should not be allowed to attend school. Schools should advise them to seek medical advice and avoid school till two days after fever subsides.
In addition, staff of schools and institutions should check their temperature before work every day and those with fever or respiratory illnesses should refrain from work.
The spokesman reminded that schools should promptly make a report to the CHP in the case of an increase in respiratory illnesses or absenteeism for immediate epidemiological investigations and outbreak control.
　
"According to the latest data, the currently circulating viruses in Hong Kong, including the influenza A (H1) and (H3) and influenza B viruses, were antigenically similar to the components of the northern hemisphere seasonal influenza vaccine (SIV) used in the 2018-19 season in Hong Kong as recommended by the Scientific Committee on Vaccine Preventable Diseases under the CHP," the spokesman said.
"Particularly, children, people aged 50 to 64 years, the elderly and those with underlying illnesses who have not yet received influenza vaccination this season 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 stressed.
As of December 23, 2018, about 381 000 and 477 000 doses of SIV had been administered via the Government Vaccination Programme and Vaccination Subsidy Scheme (VSS) (including Enhanced VSS Outreach Vaccination) respectively, increasing by 3.2 per cent and 91.6 per cent from the same period in the 2017-18 season, whereas 184 primary schools have conducted vaccination activities via the School Outreach Vaccination Pilot Programme with around 106 000 doses of SIV administered. Under the VSS (including Enhanced VSS Outreach Vaccination), 210 primary schools have conducted vaccination activities with around 71 000 doses of SIV administered.
Globally, influenza activity continued to increase in the temperate zone of the northern hemisphere and influenza A(H1) accounted for the majority of influenza detections. The 2018-19 winter influenza season has already started in Japan, Korea, Canada and the United States. The seasonal influenza activity has also been increasing in Europe including the United Kingdom. In the Mainland, most provinces have entered the influenza season and the influenza activity has continued to increase, with the predominant circulating virus being influenza A(H1). In Guangdong, influenza activity has also increased to a level above the baseline threshold since early December and the predominating virus was also influenza A(H1).
Besides receiving SIV 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.
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