Seasonal influenza: transmission, prevention and key facts

Essentials

Acute respiratory infection whose intensity and circulation vary by season and population.

Agent: Influenza A and B viruses
Transmission or exposure: Respiratory

Situation and vulnerability

Pregnant women, the elderly, young children and people with certain chronic diseases may have more complications.

Signs and limits of their interpretation

Sudden onset with fever, cough, muscle pain, fatigue and headache can evoke flu. These signs overlap with those of other respiratory infections; they do not identify the virus alone. Some people may develop pneumonia or aggravation of their chronic disease.

Diagnosis and monitoring

The diagnosis takes into account the circulation of viruses, the symptoms and, where appropriate, respiratory sampling. In a vulnerable person or with severe signs, consultation and therapeutic decision-making should not be replaced by an isolated self-test.

Check these benchmarks in the WHO reference →

Prevention and care

Seasonal vaccination and respiratory measures complement each other. Antivirals are evaluated by a physician, especially for people at risk.

Practical issues

When to ask for a quick opinion?

If breathing becomes difficult or if you belong to a group at risk, ask for advice quickly; do not wait for a test to confirm the flu.

Is a flu a simple cold?

No. Symptoms may be similar, but agents and possible complications differ. Gravity and terrain must be assessed.

Preparing for an exchange with a professional

Start date and evolution of symptoms
Pregnancy, age, chronic diseases and treatments
Respiratory difficulties, hydration and contact with fragile people

Bring the full minutes and dates. This information facilitates evaluation; its collection must not delay an urgent appeal.

Individual decisionThe choice of a test, treatment or prevention depends on the local situation and recommendations. In case of distress, call 911.