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.
Symptoms of influenza
The doctor will look to see if some or most of the symptoms of influenza are present. During an epidemic flu-type symptoms are sufficient to diagnose an influenza infection.
From the announcement that the influenza virus is in circulation, every influenza-type syndrome is probably influenza unless the contrary can be proved. However, this does not mean that the virus involved is identified.
Nose and throat swab
In doubtful cases, the doctor may take a nose and throat swab (respiratory sample) in the 7 days following the onset of the symptoms. This sample is then sent to a laboratory to diagnose the virus involved.
A single blood sample to screen for antibodies is not effective in diagnosing influenza. Two samples must be taken at an interval of 2 weeks for definite confirmation of an increase in antibodies. The result therefore becomes available at the time of convalescence and so is of little interest to the patient.
The aim of serological diagnosis is to check the efficacy of the vaccine and to carry out epidemiological studies (scientific studies of diseases in a population according to different criteria: geographical, sex, how they occur and spread).