Alternate Names : Flu Shot, Influenza Immunization, Influenza Vaccine
The flu vaccine involves the injection of inactivated viruses to
protect against influenza, commonly known as the flu.
What is the information for this topic?
There are 3 types of influenza viruses: influenza A, B, and C. Each of
these has several subtypes. All of these forms of the virus mutate, or change
their genes slightly, so they vary from year to year. That is why a new flu
vaccine has to be developed every year. The vaccine is made according to what
experts think will be the most common flu viruses to infect people during the
following winter. The vaccine has a 60% to
70% success rate in preventing the different types of influenza viruses each
It takes about 2 weeks for a person to develop immunity after having a flu
shot. The flu season usually begins
in late October or early November and goes through the early spring. The most
cases occur in January and February.
The vaccine is recommended for people considered to be at high risk,
including the following:
people over age 50
children and adults with
heart disease and lung disease, including asthma
people who live in nursing homes or other institutional settings
people who have a chronic disease such as diabetes, asthma, anemia, or
people who can transmit the flu to others at high risk. This group
includes healthcare workers, and employees of facilities that care for people
at high risk.
women who will be in the second or
third trimester of pregnancy during
the flu season
people whose immune system is weakened because of chemotherapy
people with HIV, or AIDS
A recent study showed that the flu vaccine may also be effective in preventing
second heart attacks in people who have already had a heart attack. In the study, people who received the flu
vaccine had a 67% lower incidence of a second heart attack than the people who
were not vaccinated that year.
Elderly individuals who are vaccinated against the flu have a significantly
lower incidence of hospitalization for respiratory disease, congestive heart failure, and death from any
About 25% of adults who receive the flu vaccine report mild soreness at
the site of the injection. Young children may develop fever after a flu
vaccine. In past years, administration of the flu vaccine was associated with
Guillain-Barre syndrome, a rapidly progressive weakness that
sometimes causes paralysis. However, this is no longer the case.
There is a risk of an allergic reaction to the vaccine, with possible
itching, trouble breathing, or shock. A person who has had this problem in the past
should tell the person giving the shot about it. He or she may decide not to
administer the vaccine in order to avoid the chance of a repeat reaction.
Individuals who should not get flu shots include the following:
people allergic to eggs
people with fever or illness
more serious than a cold at the time
of the shot
individuals who have had allergic reactions to the flu
people who have suffered paralysis from
A nasal vaccine for the flu is being
tested and may soon be available.
A person who develops a high fever
(a temperature above 100.5 degrees Fahrenheit or 38 degrees centigrade) or an allergic
reaction after the shot should call the healthcare provider. The
provider can also discuss other questions or concerns about flu shots.