The Centre for Health Protection (CHP) of the Department of Health today (January 9) 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 2019/20 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 (PHLSB), the percentage that tested positive for seasonal influenza A and B viruses has increased steadily since mid-December last year and rose to 10.09 per cent last week, ending January 4 this year, which was above the baseline threshold of 9.21 per cent. The circulating influenza viruses in the past two weeks were predominately influenza A(H1) (around 66.3 per cent) and A(H3) (around 30.4 per cent), with very few influenza B positive detections.
 
     The overall admission rate with principal diagnosis of influenza in public hospitals has been increasing to 0.40 per 10 000 population last week, which was above the baseline threshold of 0.25.
 
     The number of institutional influenza-like illness outbreaks reported to the CHP was four in the past two weeks, affecting 15 persons. In the first four days of this week, the CHP recorded 23 outbreaks, affecting 95 persons. The recorded outbreaks included nine in primary schools, seven in kindergartens/child care centres, five in residential care homes for the elderly, two in residential care homes for persons with disabilities, two in secondary schools, one in a residential child care centre and one in a hospital. 
 
     The CHP will issue letters to doctors, hospitals, institutions and schools to appeal for heightened vigilance and appropriate actions. To prevent transmission of influenza in school environments, schools are reminded to take additional measures, including actively checking 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. Schools should promptly make a report to the CHP in the case of an increase in fever or respiratory illnesses or absenteeism for immediate epidemiological investigations and outbreak control.
 
     As for regions outside Hong Kong, influenza activity continued to increase in the temperate zone of the northern hemisphere. The winter influenza season has already started in the United States (US), Canada, Europe, the United Kingdom (UK), Japan, Mainland China, Macao and Taiwan. Different subtypes of viruses circulate with varying proportions in different regions. Influenza A(H3) virus predominate in Europe, the UK and Mainland China (including southern and northern provinces) while influenza A(H1) was the predominant circulating virus in places such as the US, Japan and Taiwan. In the US and southern provinces in Mainland China, influenza B was also one of the predominant circulating viruses. 
 
     The spokesman reminded those who have plans to travel during the Lunar New Year to pay special attention to the influenza situations of their travel destinations before departure. As it takes about two weeks to develop antibodies, members of the public aged 6 months or above are advised to receive seasonal influenza vaccines (SIVs) early for protection against seasonal influenza. Furthermore, travellers to areas affected by influenza should adopt appropriate personal protective measures and take heed of personal hygiene and may consider putting on surgical masks when staying in crowded or poorly ventilated public places.
 
     The results of antigenic characterisation of influenza viruses performed by the PHLSB of the CHP showed that the majority of influenza A(H1) and influenza B viruses detected in late November and December 2019 were antigenically similar to the vaccine strains contained in the 2019/20 Northern Hemisphere SIV. However, the influenza A(H3) viruses tested were antigenically dissimilar from the H3 vaccine strain. For the time being, there is no relevant data on vaccine effectiveness of the 2019/20 Northern Hemisphere SIV overseas. The CHP will continue to closely monitor local and global influenza activity, predominating strains, vaccine effectiveness and relevant scientific literature.
 
     Of note, the quadrivalent influenza vaccines commonly used in Hong Kong can provide protection against four influenza viruses, namely influenza A(H1), influenza A(H3), influenza B(Victoria lineage) and influenza B(Yamagata lineage). Even if the effectiveness against one of the vaccine strains might be lower, the influenza vaccines can still provide protection against the other vaccine strains. The vaccines also provide a certain degree of cross-protection against different but related strains, thereby reducing disease severity and complications, particularly for high-risk persons such as children, the elderly and those with underlying illnesses. Therefore, vaccination remains one of the most effective ways to prevent seasonal influenza. Medical advice should be sought promptly 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 Government has launched in phases various seasonal influenza vaccination programmes since October last year to provide eligible members of the public aged 6 months or above, including children, persons aged 50 years or above and the elderly, with free or subsidised vaccination of SIV.
 
     As of January 5, about 482 000 and 427 000 doses of SIV had been administered via the Government Vaccination Programme and the Vaccination Subsidy Scheme respectively. In addition, some 430 primary schools and 700 kindergartens/child care centres had participated in the Seasonal Influenza Vaccination School Outreach (Free of Charge). Around 206 000 and 79 000 doses of SIV were administered at primary schools and kindergartens/child care centres respectively. In total, around 1 190 000 doses of doses of SIV were administered via the aforementioned vaccination programmes, increasing by 17 per cent from the same period in the 2018-19 season.
 
     Apart from getting influenza vaccination, members of the public should maintain good personal and environmental hygiene during influenza seasons both locally and during travel. People should always take the following preventive measures:
 

• Perform hand hygiene frequently, especially before touching the mouth, nose or eyes; after touching public installations such as handrails or door knobs; or when hands are contaminated by respiratory secretion after coughing or sneezing.
• Wash hands with liquid soap and water, and rub for at least 20 seconds. Then rinse with water and dry with a disposable paper towel. If hand washing facilities are not available, or when hands are not visibly soiled, performing hand hygiene with a 70 to 80 per cent alcohol-based handrub is an effective alternative. To perform hand hygiene properly, please browse the following webpage: www.chp.gov.hk/en/healthtopics/content/460/19728.html.
• Cover your mouth and nose with tissue paper when sneezing or coughing. Dispose of soiled tissues into a lidded rubbish bin, then wash hands thoroughly.
• When having respiratory symptoms, wear a surgical mask, refrain from work or attending class at school, avoid going to crowded places and seek medical advice promptly.
• Build up good body immunity by having a balanced diet, regular exercise, adequate rest, reducing stress, not smoking and avoiding alcohol consumption. 
• Regularly clean and disinfect frequently touched surfaces such as furniture, toys and commonly shared items with 1:99 diluted household bleach (mixing one part of 5.25 per cent bleach with 99 parts of water), leave for 15 to 30 minutes, and then rinse with water and keep dry. For metallic surfaces, disinfect with 70 per cent alcohol.
• Use absorbent disposable towels to wipe away obvious contaminants such as respiratory secretions, and then disinfect the surface and neighbouring areas with 1:49 diluted household bleach (mixing one part of 5.25 per cent bleach with 49 parts of water), leave for 15 to 30 minutes and then rinse with water and keep dry. For metallic surfaces, disinfect with 70 per cent alcohol.
• Maintain good indoor ventilation. Avoid going to crowded or poorly ventilated public places; high-risk individuals may consider putting on surgical masks while in such places.

Ends/Thursday, January 9, 2020
Issued at HKT 13:00

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