Seasonal influenza

Clinical picture

Influenza is a respiratory infectious disease caused by the influenza virus.

The symptoms may vary from mild to very serious, sometimes even fatal. In about 50% of cases, the infection is sub-clinical, especially in adults.

The symptoms can persist for 2-6 days, full recovery within 1-3 weeks.

Elderly people (65 years and over) and people with a chronic condition are more likely to suffer from a (more) serious progress of the disease and complications.

Additional information from the RIVM.

Infection route

Infection usually occurs by way of small droplets in the air, coughing or sneezing. Infection can also occur through direct contact with contaminated hands or objects (door handle).

Contagious period

Virus is excreted from the day before symptoms occur until usually 5 to 7 days after the onset of symptoms.

Incubation time

The incubation period is 1 to 5 days (usually 3-4 days).

Potential infectees

All staff who come into contact with influenza patients (or material contaminated with influenza) may be infected with the influenza virus. This is most likely to occur in confined, crowded areas.

Vulnerable groups are: staff with chronic suffering (e.g. diabetes mellitus), heart and lung diseases.


Training: Information must be available to staff, e.g. via a leaflet or the intranet.

General measures: Follow up on internal hygiene measures, drawn up by the hospital hygiene department.

Vaccination: Provide annual seasonal vaccination to health care workers for reasons preventing infection of clients/patients (see potential infectors).

Post-exposure policy


Potential infectors

Staff who are contagious and have direct contact with patients.