In most cases influenza is a benign illness but for elderly people, pregnant women and people with chronic diseases, the complications of flu can be dangerous. Vaccination remains the best way of preventing the complications of flu and hospitalisation.

What is the difference between influenza and the common cold?

Influenza is an infection with symptoms at the upper respiratory tract (nose, throat, bronchial tubes) the symptoms of which are often confused with those of a cold.

While a cold can cause a slight increase in temperature, influenza usually results in a sudden rise in temperature to over 38°

It is accompanied also by muscle aches, chills sweating and a general feeling of tiredness and weakness.

Comparative table of symptoms

Symptoms Influenza Common cold
Headache x x
Sore throat x x
Runny nose x x
Cough x x
Incubation perdiod 1<3 days 2<5 days
Fever x  
Chills / sweating x  
Weakness /fatigue x  
Muscles aches  x  

Other respiratory tract viruses can also cause symptoms that resemble those of influenza.

DID YOU KNOW? The incubation period is the period between contamination and appearance of the first symptoms.

Development of influenza

Influenza is contagious for 1 to 2 days before the appearance of symptoms and up to 4-5 days after:

  • the first symptoms of influenza appear from 1 to 3 days after infection
  • the infection generally lasts for 1 week and recovery takes 2 weeks without medical treatment
  • children may be subject to vomiting and have diarrhoea.

In more serious cases, the development of influenza may be very fast and prove fatal.

Sciensano coordinates a network of general practitioners and hospitals to ensure the permanent surveillance of influenza activity, of the intensity and severity of epidemics and the impact on the population. Sciensano is also the National Reference Centre (NRC) for influenza virus. The Belgian Official Medicines Control Laboratory (OMCL) of Sciensano, together with the European OMCL network, is responsible for the quality control of the influenza vaccine prior to marketing.

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