- Slideshow: Foods to Eat When You Have the Flu
- Slideshow: Natural Cold & Flu Remedies
- Slideshow: Finding Relief for Your Cough
- Patient Comments: Flu (Influenza) - Symptoms
- Patient Comments: Flu (Influenza) - Side Effects
- Flu (influenza, conventional, H1N1, H3N2, and bird flu [H5N1]) facts
- What is flu (influenza)?
- When does flu season begin and end?
- Flu vs. cold
- What are the causes of the flu (influenza)?
- What are flu (influenza) symptoms in adults and in children?
- What is the incubation period for the flu?
- How long is the flu contagious, and how long does the flu last?
- How is the flu (influenza) diagnosed?
- How does flu spread?
- What is the key to flu (influenza) prevention?
- Are there any flu shot or nasal spray vaccine side effects in adults or in children?
- How effective is the flu vaccine?
- Why should the flu (influenza) vaccine be taken every year?
- What are some flu treatments an individual can do at home (home remedies)?
- What types of doctors treat the flu?
- What can people eat when they have the flu?
- When should a person go to the emergency department for the flu?
- Who should receive the flu vaccine, and who has the highest risk factors? When should someone get the flu shot?
- What is the prognosis for patients who get the flu? What are possible complications of the flu?
- Can the flu be deadly?
- What is the bird (avian) flu?
- Do antiviral agents protect people from the flu?
- What medications treat the flu?
- Is it safe to get a flu shot that contains thimerosal?
- Where can people find additional information about the flu?
Quick GuideFlu Pictures Slideshow: 10 Foods to Eat When You Have the Flu
How effective is the flu vaccine?
Vaccine efficacy also varies from one person to another. Past studies of healthy young adults have shown influenza vaccine to be 70%-90% effective in preventing illness. In the elderly and those with certain chronic medical conditions such as HIV, the vaccine is often less effective in preventing illness. Studies show the vaccine reduces hospitalization by about 70% and death by about 85% among the elderly who are not in nursing homes. Among nursing-home residents, vaccine can reduce the risk of hospitalization by about 50%, the risk of pneumonia by about 60%, and the risk of death by 75%-80%. However, these figures did not apply to the 2014-2015 flu vaccine because the quadrivalent (four antigenic types) vaccine did not match well with 2014-2015 circulating strains of the flu (vaccine effectiveness was estimated to be 23%). This occurs because the vaccine needs to be produced months before the flu season begins, so the vaccine is designed by projecting and choosing the most likely viral strains to include in the vaccine. If drift results in changing the circulating virus from the strains used in the vaccine, efficacy may be reduced. However, the vaccine is still likely to lessen the severity of the illness and to prevent complications and death, according to the CDC.
Recent studies suggest that in younger children (ages 2-8) the nasal spray flu vaccine may prevent about 50% more cases of flu than the vaccine administered by the flu shot. Therefore, children in this age group who have no contraindications should receive this form of the vaccine if it is available. However, the CDC recommends that vaccination not be delayed if this form is not available; the flu shot should be given in this case.