Influenza (flu) is an acute illness of the respiratory tract caused by influenza viruses. It is usually more common in periods from January to March and from July to August in Hong Kong. New subtype variants appear from time to time and at irregular intervals. Antigenic drifts (minor changes) of influenza viruses lead to the emergence of new viral strains every year. These minor changes cause seasonal influenza and explain why reformulation of the influenza vaccine is required every year.
For healthy individuals, seasonal influenza is usually self-limiting with recovery in 2 – 7 days. Symptoms may include fever, cough, sore throat, runny nose, muscle pain, fatigue and headache; some may also have vomiting and diarrhoea.
Cough is often severe and prolonged but fever and other symptoms generally resolve in 5 – 7 days. However, influenza can be a serious illness to the weak and frail or elderly people, and may be complicated by bronchitis, chest infection or even death.
Mode of Transmission
Influenza viruses mainly spread through droplets when infected people cough, sneeze or talk. The infection may also spread by direct contact with the secretions of infected persons.
PreventionSeasonal influenza vaccination
In addition, members of the public should also maintain balanced diet, exercise regularly, take adequate rest, do not smoke and avoid overstress.
Ref : www.chp.gov.hk
last update：10 Aug 2018
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