The Centre for Health Protection (CHP) of the Department of Health today (January 3) reported that local seasonal influenza activity has been increasing in the past two weeks, and appealed to the community for heightened vigilance as Hong Kong will enter the winter influenza season soon.
 
     "Our latest surveillance data show that the local seasonal influenza activity steadily increased from a baseline level. We anticipate that the seasonal influenza activity will continue to increase and the winter influenza season in Hong Kong will arrive soon. Members of the public should maintain good personal protection against influenza," a spokesman for the CHP 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.
 
     The positive percentage of seasonal influenza viruses among respiratory specimens received by the CHP increased from 3.93 per cent in the week ending December 16 to 6.02 per cent and 9.32 per cent in the following two weeks. The circulating influenza viruses in the past two weeks 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 161.3 cases per 1 000 coded cases to 170.2 and 196.1. The overall admission rate with principal diagnosis of influenza in public hospitals increased from 0.09 per 10 000 population to 0.15 and 0.23.
 
      As of December 26, 2017, about 369 100 and 244 600 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 10.0 per cent and 3.4 per cent from the same period in the 2016-17 season.
 
     The CHP has enhanced surveillance in preparation for the winter influenza season. Since 2018, the CHP has collaborated with public hospitals under the Hospital Authority and private hospitals to monitor influenza-associated admissions to intensive care units and deaths among patients aged 18 years or above as routine surveillance operating throughout the year.
 
     The CHP will issue letters to doctors, hospitals, institutions and schools to appeal for heightened vigilance and appropriate actions.
 
     Following the end of the Christmas and New Year holidays, the management of schools should stay alert to seasonal influenza, which may lead to outbreaks when classes resume. Schools are reminded to actively check the body temperature of all students every day when they arrive at school to identify those with fever. The CHP will issue letters to kindergartens and child care centres as well as primary and secondary schools on the above additional measure. To prevent outbreaks, those with fever (oral temperature over 37.5 degrees Celsius or ear temperature over 38 degrees), 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 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 respiratory illnesses or absentees for immediate epidemiological investigations and outbreak control," the spokesman said.
 
     Globally, influenza activity continued to increase in the temperate zone of the northern hemisphere. Worldwide, influenza A(H3N2) and B viruses accounted for the majority of influenza detections. The 2017-18 winter influenza season has already started in the United States, Canada, the United Kingdom and Japan. In North America, influenza A (H3N2) was the predominating virus. In Europe, influenza A and influenza B viruses were co-circulating.
 
     In Mainland China, the winter influenza season has arrived in both southern and northern China with an increasing trend of influenza activity. In southern China, the proportion of ILI cases in emergency and outpatient departments reported by sentinel hospitals was 4.3 per cent in the week ending December 24, higher than that reported in the previous week (3.7 per cent) and the figures in the corresponding periods in 2014-16 (2.4 per cent, 2.8 per cent and 3.3 per cent). In northern China, that proportion was 5.2 per cent, higher than that reported in the previous week (4.9 per cent) and the figures in the corresponding periods in 2014-16 (3.9 per cent, 2.7 per cent and 3.5 per cent). The positive percentage of influenza detections was 40.2 per cent. The predominant circulating virus was influenza B (78.1 per cent in southern China and 55.7 per cent in northern China).
 
     In Guangdong, the influenza activity has been increasing in the past few weeks. In the week ending December 24, the proportion of ILI cases among sentinel hospitals was 4.90 per cent as compared with 3.96 per cent in the previous week. The percentage of respiratory specimens tested positive for influenza was 20.75 per cent as compared with 14.11 per cent in the previous week. The predominant virus was influenza B. This winter influenza season arrived earlier than those of the past two years and the surveillance indicators showed that the influenza activity was higher than that in the same period in the past few years. However, the overall influenza activity in Guangdong so far has been within the expected range. 
 
      In Taiwan, the influenza season has also arrived with increasing influenza activity. In the week ending December 30, the proportion of ILI cases in emergency departments was 12.7 per cent, which was above the threshold of 11.4 per cent. The predominating virus was influenza B, which constituted 77 per cent of the influenza detections.
 
      The CHP's Port Health Office conducts health screening measures at all boundary control points. Thermal imaging systems are in place for body temperature checks on inbound travellers. The display of posters and broadcasting of health messages in departure and arrival halls as health education for travellers is under way.
 
     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:
 

• 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 as an effective alternative;
• 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 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 influenza page and weekly Flu Express for more information.

Ends/Wednesday, January 3, 2018
Issued at HKT 17:55

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