What should you know about human influenza virus?

Influenza spreads mainly through respiratory particles and close contact. People may develop chills, fever, cough, headache, fatigue and a general feeling of being unwell. Symptoms can overlap with COVID-19 and other infections, so symptoms alone cannot identify the virus. Influenza can sometimes lead to pneumonia, particularly when illness is severe or a person has medical conditions that affect their resilience.

A healthcare professional may assess your symptoms, examination findings and risk factors. Testing can be useful in some settings, especially when the result could change treatment or infection-control advice.

Rest, drink fluids and limit close contact while you are unwell. Cover coughs, wash hands and improve ventilation around others. Ask a clinician early about antiviral treatment if symptoms are significant or you are pregnant, older, immunocompromised or living with a long-term condition. Do not start antibiotics unless prescribed; they do not target influenza virus.

Seek urgent care for difficulty breathing, chest pain, confusion, fainting, severe dehydration, blue or grey lips, or symptoms that improve and then become markedly worse. Contact a clinician if fever persists, you cannot keep fluids down, or you are in a higher-risk group.

Ask whether testing or antiviral medicine is useful, how to protect household members, when you can return to work or school, and whether pneumonia needs to be considered.