Influenza Questions and Answers
What is influenza (Flu) and how is it caused?
Influenza is a contagious disease caused by a virus. Influenza viruses infect many parts of the body, including lungs.
When someone who has influenza sneezes, coughs or even talks, the influenza virus is expelled into the air and may be inhaled by anyone close by.
What are the symptoms of influenza?
Influenza is a highly contagious respiratory viral illness. Influenza A and B are the major types of influenza viruses that cause human disease and affect people of all ages.
Persons with influenza may have fever, cough, sore throat, fatigue, muscle aches, headaches, runny nose and watery eyes.
Children may experience vomiting and diarrhea in addition to these symptoms. Although the fever and body aches usually last for 3-5 days, a cough and fatigue may persist for 2 weeks or more.
How long is a person with influenza contagious?
The period between infection and onset of symptoms (incubation period) for influenza is 1-4 days. A person with influenza may be contagious for 3-7 days after the onset of symptoms. Children may be contagious for longer than 7 days.
How can influenza and its complications be prevented?
Influenza can be prevented with a high degree of success when a person receives the current influenza vaccine. This vaccine is made each year so that the vaccine contains the influenza strains that are expected to cause illness in that year.
Is the influenza vaccine safe?
The vaccine does not cause influenza. It does not contain 'live virus'. Generally, people have no reaction to the vaccine. Some people may experience mild side effects such as tenderness and redness at the injection site. These side effects usually clear within a day.
Persons with allergies to eggs or chicken products should not receive influenza vaccine, as it is prepared from influenza viruses grown in eggs.
How effective is influenza vaccine?
In years in which there is a good match between the vaccine virus and the virus strain causing illness, influenza vaccine is generally considered to be 70%-90% effective in preventing influenza illness in healthy adults.
It is important to know that it takes about 2 weeks after influenza vaccination for a person to develop protection against influenza infection. Also, influenza vaccine does not protect against respiratory illness caused by other viruses.
Can you get influenza from a vaccination?
No, it is absolutely impossible to get influenza from the vaccine. The viruses in the vaccine are inactivated and incapable of causing influenza. Instead, the person is protected from influenza by antibodies that are formed by the immune system's response to the vaccine.
The amount of antibodies in the body is greatest 1 or 2 months after vaccination and then gradually declines. For that reason and because the influenza viruses usually change each year, a high-risk person should be vaccinated each Autumn with the new vaccine.
Is influenza considered serious?
For healthy children and adults, influenza is typically a moderately severe illness. Most people are back on their feet within a week.
For people who are not healthy or well to begin with, influenza can be very severe and even fatal. Symptoms have greater impact on these people, in addition, complications can occur. Most of these complications are bacterial infections because the body can be severely weakened by influenza such that its defences against bacteria are low. Bacterial pneumonia is the most common complication of influenza. Also, the sinuses and inner ears may become inflamed and painful.
Who gets influenza?
Anyone can get influenza, especially when it is widespread in the community. People who are not healthy or well to begin with are particularly susceptible to the complications that can follow. For anyone in a high risk category, influenza is a very serious and potentially fatal illness.
The National Health and Medical Research Council recommends annual vaccination for:
- All individuals over 65 years of age*
- Aboriginal and Torres Strait Islander people aged 50 years and older or aged 15-49 with risk factors*
- Adults and children (above 6 months of age) with:
- Chronic suppurative lung disease, including bronchiectasis, cystic fibrosis and chronic emphysema
- Chronic (long-term) heart conditions including cyanotic congestive heart disease, coronary heart disease and congestive heart disease
- Chronic illnesses requiring regular medical follow-up or hospitalisation in the preceding year, including diabetes mellitus, chronic metabolic diseases, chronic renal failure, haemoglobinopathies or immunosuppression, severe asthma
- Immune deficiency, including HIV, malignancy and chronic steroid use
- Residents of nursing homes or other long-term facilities and contacts of high risk patients, including health-care providers, staff of nursing homes and long-term care facilities and household members of persons in high-risk groups
- Children aged 6 months to 10 years on long-term aspirin therapy