All About the Influenza Virus

The flu (influenza) is a contagious disease caused by a group of respiratory viruses called influenza viruses. The influenza virus is highly contagious and causes serious illness that may result in hospitalisation or death. It mostly affects the breathing system but may also affect the whole body.

When the term flu' is used, we are referring to influenza virus infection. In the community, some people might use the word flu to refer to viral gastroenteritis (vomiting and diarrhoea) or any disease that causes influenza-like illness. Each year, the flu season is different. It is not possible to know whether the flu season will start early or later in the autumn or winter. You can usually tell when an outbreak is occurring in your community by following various forms of media coverage, or by checking with your local health department.

What Are Flu Symptoms?

Flu symptoms include sudden onset of fever, abdominal pain, chills, cough, croup, bronchiolitis or pneumonia, decreased energy or feeling a lot more tired than usual, headache, muscle aches and pains, nasal congestion, nausea, and sore throat.

More than one-third of children younger than six may be infected with an influenza virus each year. However, some infected children do not show signs or symptoms of illness. Influenza looks like other common cough and cold viruses, but can be more serious. We do not know which children with respiratory illnesses have influenza.

During a local influenza outbreak, the chances of a child having influenza increase, but most respiratory illnesses are still caused by viruses other than influenza. Common cold viruses may cause fever, but generally they do not lead to serious illness requiring hospitalisation.

When Do Children Spread Influenza?

Children (and adults) can spread influenza when they are:

• Sick with fever, runny nose, sore throat, and cough
• Infected but not showing signs of illness
• Developing an illness (incubation period)
• Recovering from influenza

Influenza viruses are shared or transmitted' in droplets that form when a child coughs or sneezes. These droplets either land directly on another child's mucous membranes (eyes, nose, or mouth) or fall to surfaces that are touched by another child, who then touches her own mucous membranes.

Influenza Vaccine

Seasonal influenza vaccines are the best available protection against flu. Protection from the vaccine only lasts for one flu season. The influenza virus strains can change each year, so the vaccine has to also change to cover the anticipated new influenza viruses. That's why protection needs updating every year. The American Academy of Pediatrics (AAP) recommends that everyone six months and older gets the flu vaccine every year.