Some people get much sicker. Influenza can lead to pneumonia
and can be dangerous for people with heart or breathing conditions. It can
cause high fever and seizures in children. On average, 226,000 people are
hospitalized every year because of influenza and 36,000 die - mostly elderly.
vaccine, or the "flu shot," is given by injection into the
Live, attenuated (weakened)
influenza vaccine, called LAIV, is sprayed into the nostrils. For more
information about this vaccine, see the topic Vaccine Information
For most people, influenza vaccine prevents serious
influenza-related illness. But it will not prevent
"influenza-like" illnesses caused by other viruses.
viruses are always changing. Because of this, influenza vaccines are updated
every year, and an annual vaccination is recommended. Protection lasts up to a
It takes up to 2 weeks for protection to develop after the
Some inactivated influenza vaccine contains
thimerosal, a preservative that contains mercury. Some people believe
thimerosal may be related to developmental problems in children. In 2004 the
Institute of Medicine published a report concluding that, based on scientific
studies, there is no evidence of such a relationship. If you are concerned
about thimerosal, ask your doctor about thimerosal-free influenza vaccine.
Who should get inactivated influenza vaccine?
People 6 months of age and older can receive inactivated
influenza vaccine. It is recommended for anyone who is at risk of complications from influenza or more likely to require medical care :
All children from 6 months up to 5 years of
Anyone 50 years of age or older.
Anyone 6 months
to 18 years of age on long-term aspirin treatment (they could develop Reye
Syndrome if they got influenza).
Women who will be pregnant during
Anyone with certain muscle or nerve disorders
(such as seizure disorders or severe cerebral palsy) that can lead to breathing
or swallowing problems.
Residents of nursing homes and other
Influenza vaccine is also recommended for anyone who lives with or cares for people at high risk for influenza-related complications :
Health care providers.
contacts and caregivers of children from birth up to 5 years of age.
Household contacts and caregivers of people 50 years and older,
and those with medical conditions that put them at higher risk for severe
complications from influenza.
A yearly influenza vaccination should be considered for:
People who provide essential community services.
People living in dormitories or under other crowded conditions, to
People at high risk of influenza complications
who travel to the Southern hemisphere between April and September, or to the
tropics or in organized tourist groups at any time.
Influenza vaccine is also recommended for anyone who wants to
reduce the likelihood of becoming ill with influenza or
spreading influenza to others .
When should I get influenza vaccine?
Plan to get
influenza vaccine in October or November if you can. But getting vaccinated in
December, or even later, will still be beneficial in most years. You can get
the vaccine as soon as it is available, and for as long as illness is
occurring. Influenza illness can occur any time from November through May. Most
cases usually occur in January or February.
Most people need one
dose of influenza vaccine each year. Children younger than 9 years of age
getting influenza vaccine for the first time should get 2 doses. For
inactivated vaccine, these doses should be given at least 4 weeks apart.
Influenza vaccine may be given at the same time as other vaccines,
including pneumococcal vaccine.
Some people should talk with a doctor before getting influenza vaccine
people should not get inactivated influenza vaccine or should wait before
Tell your doctor if you have any severe
(life-threatening) allergies. Allergic reactions to influenza vaccine are rare.
Influenza vaccine virus is grown in eggs.
People with a severe egg allergy should not get the vaccine.
severe allergy to any vaccine component is also a reason to not get the
If you have had a severe reaction after a previous dose
of influenza vaccine, tell your doctor.
Tell your doctor if you ever had Guillain-Barré
Syndrome (a severe paralytic illness, also called GBS). You may be able to get
the vaccine, but your doctor should help you make the
People who are moderately or severely ill should usually
wait until they recover before getting flu vaccine. If you are ill, talk to
your doctor or nurse about whether to reschedule the vaccination. People with a
mild illness can usually get the vaccine.
What are the risks from inactivated influenza vaccine?
A vaccine, like any medicine, could possibly
cause serious problems, such as severe allergic reactions. The risk of a
vaccine causing serious harm, or death, is extremely small.
Serious problems from influenza vaccine are very rare.The viruses in
inactivated influenza vaccine have been killed, so you cannot get influenza
from the vaccine.
soreness, redness, or swelling where the shot was
If these problems occur, they usually begin soon after the
shot and last 1-2 days.
Life-threatening allergic reactions from vaccines
are very rare. If they do occur, it is within a few minutes to a few hours
after the shot.
In 1976, a certain type of influenza (swine flu)
vaccine was associated with Guillain-Barré Syndrome (GBS). Since then, flu
vaccines have not been clearly linked to GBS. However, if there is a risk of
GBS from current flu vaccines, it would be no more than 1 or 2 cases per
million people vaccinated. This is much lower than the risk of severe
influenza, which can be prevented by vaccination.
Maria G. Essig, MS, ELS
Susan Van Houten, RN, BSN, MBA
Pat Truman, MATC
Primary Medical Reviewer
Kathleen Romito, MD - Family Medicine
Specialist Medical Reviewer
W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
July 31, 2008
WebMD Medical Reference from Healthwise
July 31, 2008
This information is not intended to replace the advice of a doctor.
Healthwise disclaims any liability for the decisions you make based on this