Purpose

This paper explains the current situation of influenza infection in Hong Kong and the preventive and control measures which have been put in place.

Background

2. Influenza is an acute respiratory infection transmitted by the airborne route. In the vast majority of cases, influenza is self-limiting and patients recover completely. Elderly people and people with chronic heart or lung diseases may have a higher chance of developing complications, such as pneumonia.

3. Influenza is a common disease in Hong Kong. It has higher prevalence around March and July every year. This year's situation is the same as before, with the number of influenza cases starting to increase since late February. The predominant strain in previous years was the Wuhan strain, but it has been replaced by the Sydney strain this year. Both strains are subtypes of influenza A H3N2 viruses.

4. Similar to previous years, influenza activity in 1998 increased gradually since early February. The recorded rate of influenza-like-illnesses (ILI) in General Outpatient Clinics (GOPCs) rose from 7.8 per 1,000 consultations in January to 15 per 1,000 consultations in February. The recorded ILI rate in private clinics increased from 41.9 per 1,000 consultations to 47.5 per 1,000 consultations in the same period.

5. During the period of February and March (up to 21 March 1998), a total of 3,891 patients with influenza-like symptoms were admitted to public hospitals. Of these, 1,582 were found to be positive for influenza A. Despite this recent increase in influenza A-positive cases, a decreasing trend has been observed over the past few weeks. Among the cases tested, the percentage of cases found to be influenza A-positive has decreased from 48% in the week beginning 22 February to 31.4% in the week beginning 15 March 1998.

Preventive and Control Measures

6. To control the occurrence of influenza in Hong Kong, we have put in place a number of measures, as described in the following paragraphs.

Surveillance

7. Effective health surveillance is vital for monitoring influenza trends and developments. Our present influenza surveillance network includes all 63 GOPCs, public hospitals, and 18 private clinics. The data collected provides the necessary information to facilitate the formulation of preventive and control measures.

Vaccination for high risk groups

8. To avoid infection of influenza among the elderly in residential care homes, the Department of Health (DH) conducted an influenza vaccination programme in the first half of February 1998 for about 40,000 elderly people living in 500 public and private elderly homes. The Department has plans to conduct another round of vaccination in the last quarter of 1998, in anticipation of the seasonal peak in February-March 1999.

9. Starting from February 1998, the Hospital Authority (HA) has also provided influenza vaccination to its elderly patients residing in infirmaries and some high risk patients, such as the mentally handicapped patients.

Measures taken by hospitals

10. To cope with the recent increase in the number of influenza A cases, the HA has set up a multi-disciplinary task force to monitor the situation and to advise on appropriate clinical management and infection-control guidelines. Relevant information is disseminated to all staff involved in handling patients with influenza.

11. Individual hospitals have identified areas which are suitable for placing suspected and confirmed cases of influenza patients, away from other patients. These areas may be expanded subject to needs. Necessary equipment and consumables are available. Individual hospitals have plans in place for internal deployment of staff, in case of need, between departments likely to be under pressure and those less busy.

Health education

12. DH has reinforced its health education programme on prevention of influenza. An influenza section has been set up in DH's homepage on the Internet, containing the latest figures and trends for public information. Specific messages on how to prevent influenza are constantly disseminated via the media, hotlines, health talks and other channels.

13. The mainstay in the prevention of influenza is to strengthen body resistance through proper diet, adequate rest and exercise, and maintaining good ventilation.

Conclusion

14. The Administration has adequate health care facilities to cope with any increase in influenza cases. The Department of Health and the Hospital Authority will monitor the situation closely and carry out appropriate preventive and follow-up measures to control the infection of influenza.



Department of Health
March 1998