Seasonal Influenza Q&A

What is seasonal influenza?

Seasonal influenza (or "flu") is an acute viral infection caused by type A or B influenza viruses. It is contagious and can spread easily from person-to-person. Seasonal influenza is characterized by a number of symptoms including

  • Sudden onset of fever,
  • Cough (usually dry),
  • Headache, muscle and joint pain, sore throat and runny nose.

The cough can be severe and can last for at least two weeks. Most people recover within a week without requiring medical attention. Influenza is however a serious public health problem that can cause severe illness and death.

How is it treated?

  • Drink plenty of water and rest
  • Antiviral drugs for influenza ideally within 48 hours after symptoms onset can reduce severe complications and deaths, but influenza viruses can develop resistant to drugs
  • Antibiotics are NOT effective against influenza viruses

How can I avoid getting the flu?

The best way to avoid getting the flu is to get the influenza vaccine every year. WHO recommends annual vaccination for high risk groups such as pregnant women, children under 5 years, the elderly, people with chronic medical condition and health care workers. People should ideally get vaccinated just before the influenza season begins (i.e. flu season in Viet Nam is normally between April – September) for the most effective coverage, although getting vaccinated at any time during the influenza season can still help prevent flu infections.

How can I prevent the flu from spreading?

WHO/Yoshi Shimizu

Influenza can spread quickly between people when an infected person coughs or sneezes, dispersing droplets containing virus into the air. It can be also spread by hands contaminated by the virus. If people have symptoms with influenza, they are encouraged to stay at home. To prevent transmission, people should cover their mouth and nose with a tissue when coughing, safely dispose the tissue and wash their hands thoroughly and regularly.

The annual incidence of influenza varies widely, depending on the virulence of circulating strains, the susceptibility of the population, vaccine coverage and vaccine match with circulating influenza viruses.

For more information, please visit:

Contact details

World Health Organization Representative Office Viet Nam
Green One UN House
304 Kim Ma St
Ha Noi
Viet Nam
Telephone: +84 24 38500100
E-mail: wpvnmmedia@who.int