Facts about Seasonal Influenza - from the World Health Organization - Part 2

Facts about Seasonal Influenza - from the World Health Organization - Part 2

Seasonal epidemics

Influenza epidemics occur yearly during autumn and winter in temperate regions. Illnesses result in hospitalizations and deaths mainly among high-risk groups (the very young, elderly or chronically ill). Worldwide, these annual epidemics result in about three to five million cases of severe illness, and about 250 000 to 500 000 deaths. Most deaths associated with influenza in industrialized countries occur among people age 65 or older. In some tropical countries, influenza viruses circulate throughout the year with one or two peaks during rainy seasons.

Disease effects

Influenza can cause serious public health and economic problems. In developed countries, epidemics can result in high levels of worker absenteeism and productivity losses. In communities, clinics and hospitals can be overwhelmed when large numbers of sick people appear for treatment during peak illness periods. While most people recover from a bout of influenza, there are large numbers of people who need hospital treatment and many who die from the disease every year. Little is known about the effects of influenza epidemics in developing countries.

Prevention

The most effective way to prevent the disease or severe outcomes from the illness is vaccination. Safe and effective vaccines have been available and used for more than 60 years. Among healthy adults, influenza vaccine can prevent 70% to 90% of influenza-specific illness. Among the elderly, the vaccine reduces severe illnesses and complications by up to 60%, and deaths by 80%.

Vaccination is especially important for people at higher risk of serious influenza complications, and for people who live with or care for high risk individuals.

WHO recommends annual vaccination for (in order of priority):

  1. nursing-home residents (the elderly or disabled)
  2. elderly individuals
  3. people with chronic medical conditions
  4. other groups such as pregnant women, health care workers, those with essential functions in society, as well as children from ages six months to two years.

Influenza vaccination is most effective when circulating viruses are well-matched with vaccine viruses. Influenza viruses are constantly changing, and the WHO Global Influenza Surveillance Network (GISN), a partnership of National Influenza Centres around the world, monitors the influenza viruses circulating in humans. WHO annually recommends a vaccine composition that targets the three most representative strains in circulation.

WHO response

WHO, with its partners, monitors influenza globally, annually recommends a seasonal influenza vaccine composition, and supports Member States efforts to develop prevention and control strategies. WHO works to strengthen national and regional influenza diagnostic capacities, disease surveillance, outbreak responses, and increase vaccine coverage among high-risk groups.

For more information contact:
Media Centre
Telephone: +41 22 791 2222
E-mail: mediaenquiries@who.int

 

Related links

:: The Global Influenza Programme

:: WHO Global Influenza Surveillance Network

:: FluNet - a web based tool for global influenza surveillance

:: Recommendations for influenza vaccines


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