Seasonal influenza

An acute respiratory infection caused by influenza viruses (mainly types A and B), with seasonal epidemics in temperate regions and year-round circulation in the tropics.

How it spreads

Droplets from coughing and sneezing, and contact with contaminated hands or surfaces.

Common symptoms

Sudden fever, dry cough, headache, muscle and joint pain, severe malaise, sore throat and runny nose; most recover within a week.

When to seek care

Shortness of breath, chest pain, persistent high fever, altered consciousness, marked lethargy or dehydration in young children; people with chronic disease and pregnant women should seek care early if worsening.

Prevention & treatment

Annual vaccination (WHO prioritises pregnant women, young children, older adults, people with chronic conditions and health workers), cough etiquette, hand hygiene, staying away from others when ill. Antivirals work best early and need clinical assessment.

Unknowns & ongoing research

Vaccine effectiveness varies year to year with the match between circulating and vaccine strains; universal influenza vaccines are still in development.

Related WHO notices

WHO Disease Outbreak News · Last successful update on this site: 2026-11-12 01:10 UTC

Official sources & interactive data