Measles; Rubella; Tetanus; Vaccinations; Whooping cough
Influenza, commonly called the flu, is always caused by a virus.
There are different strains of influenza:
Complications of the Flu. Pneumonia is the major serious complication of the flu and can be very serious. It can develop about 5 days after viral influenza. It is an uncommon event, however. It nearly always occurs in high-risk individuals, such as the very young or very old, and hospitalized or immunocompromised patients.
[For more information, see In-Depth Report #94: Colds and the flu.]
Description of Vaccines. The influenza vaccine is designed to provoke the immune system to attack antigens on the surface of the virus. (Antigens are molecules that the immune system recognizes as alien and targets for attack.)
Unfortunately, the antigens in influenza viruses undergo genetic alterations (called antigenic drift ) over time, so they are likely to become resistant to a vaccine that worked in the previous year. Vaccines are redesigned annually to match the current strain.
Until recently the vaccine has been administered only by injection. A vaccine (FluMist) that can be delivered in a nasal spray has now been approved for healthy people aged 2 - 49, who are not pregnant. The vaccine contains live viruses that have been engineered to replicate in the cool temperatures of the nasal passages, but not in the warmer lungs and lower airways. Its presence in the nasal passages boosts the specific immune factors in the mucous membranes that fight off the epidemic viruses. A preservative-free intramuscular injectable vaccine (Fluzone) is also now available.
The avian flu vaccine is designed for people aged 18 - 64 who are at risk for exposure to the avian H5N1 virus. The vaccine is given as 2 doses, spaced about 1 month apart. In studies, the vaccine appeared to be effective and well tolerated. Currently, the government is stockpiling the vaccination in case of an avian influenza outbreak. The vaccine is not available to the general public.
Ideally, appropriate candidates should be vaccinated every October or November. However, it may take longer for a full supply of the vaccine to reach certain locations. In such cases, the high-risk groups should be served first.
Antibodies to the flu virus usually develop within 2 weeks of vaccination, and immunity peaks within 4 - 6 weeks, then gradually wanes.
In healthy adults, immunization typically reduces the chance of getting the flu by about 70 - 90%. The current flu vaccines may be slightly less effective in certain patients, such as the elderly and those with certain chronic diseases. Some evidence suggests, however, that even in people with a weaker response, the vaccine is usually protective against serious flu complications, particularly pneumonia. Some evidence suggests that among the elderly, a flu shot may help protect against stroke, adverse heart events, and death from all causes.
The American Academy of Pediatrics (AAP) and the CDC recommend flu vaccinations for all healthy children ages 6 months to 18 years.
There has been some question concerning flu vaccines because of some reports that vaccines may worsen asthma. Recent and major studies have been reporting, however, that the vaccination is safe for children with asthma. It is also very important for these patients to reduce their risk for respiratory diseases.
The following, in order of priority, are the adult population groups who should be vaccinated each year. Any person not mentioned in these categories below is still encouraged to get the vaccine if they wish to avoid the flu. The first 2 groups below have the highest need for flu vaccinations and are given top priority:
Other adults who should consider flu shots include:
Possible side effects of the flu vaccine include:
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