Since the start of widespread vaccinations in the United States,
the number of cases of formerly common childhood illnesses like
have declined dramatically. Immunizations have protected millions
of kids from potentially deadly diseases and saved thousands of
lives. In fact, certain diseases crop up so rarely now that parents
sometimes ask if vaccines are even necessary anymore.
This is just one common misconception about immunizations. The
truth is, most diseases that can be prevented by vaccines still
exist in the world, even in the United States, although they occur
rarely. The reality is that vaccinations still play a crucial role
in keeping kids healthy.
Unfortunately, misinformation about vaccines could make some
parents decide not to immunize their children, putting them and
others at a greater risk for illness. To better understand the
benefits and risks of vaccines, here are a few common
What do immunizations do?
Vaccines work by preparing a child's body to fight illness.
Each immunization contains either a dead or a weakened germ, or
parts of it, that cause a particular disease.
The body practices fighting the disease by making antibodies
that recognize specific parts of that germ. This permanent or
longstanding response means that if someone is ever exposed to the
actual disease, the antibodies are already in place and the body
knows how to combat it and the person doesn't get sick. This is
Will my child's immune system be weaker by relying on a
No, the immune system makes antibodies against a germ, like the
virus, whether it encounters it naturally or is exposed to it
through a vaccine.
Will the immunization give someone the very disease it's
supposed to prevent?
This is one of the most common concerns about vaccines. However,
to get the disease from any vaccine made with dead (killed)
bacteria or viruses or just part of the bacteria or virus.
Only those immunizations made from weakened (also called
) live viruses - like the chickenpox (varicella) or measles-
(MMR) vaccine - could possibly make a child develop a mild form of
the disease, but it's almost always
much less severe
than the illness that occurs when a person is infected with the
disease-causing virus itself. However, for children with weakened
immune systems, such as those being treated for cancer, these
vaccines may cause problems.
The risk of disease from vaccination is extremely small. One
live virus vaccine that's no longer used in the United States
is the oral polio vaccine (OPV). The success of the
vaccination program has made it possible to replace the live virus
vaccine with a killed virus form known as the inactivated polio
vaccine (IPV). This change has completely eliminated the
possibility of polio disease being caused by immunization in the
Why should I have my child immunized if all the other kids in
school are immunized?
It is true that a single child's chance of catching a
disease is low if everyone else is immunized. Yet if one person
thinks about skipping vaccines, chances are that others are
thinking the same thing. And each child who isn't immunized
gives these highly contagious diseases one more chance to
This actually happened between 1989 and 1991 when an epidemic of
measles broke out in the United States. Lapsing rates of
immunization among preschoolers led to a sharp increase in the
number of measles cases, deaths, and children with permanent brain
damage. Even in 2008, the number of cases of measles in the United
States more than doubled from recent years. Most of the cases were
among people who had not been vaccinated. Similar outbreaks of
(pertussis) struck Japan and the United Kingdom in the 1970s
after immunization rates declined.
Although vaccination rates are fairly high in the United States,
there's no reliable way of knowing if everyone your child comes
into contact with has been vaccinated, particularly now that so
many people travel to and from other countries. So, the best way to
protect your child is through immunization.
Why should I subject my child to a painful shot if vaccines
aren't 100% effective?
Few things in medicine work 100% of the time, but vaccines are
one of the most effective weapons we have against disease - they
work in 85% to 99% of cases. They greatly reduce your child's
risk of serious illness (particularly when more and more people use
them) and give diseases fewer chances to take hold in a
It can be difficult to watch kids get a shot, but the short-term
pain is nothing compared with suffering through a potentially
deadly bout of diphtheria, pertussis, or measles.
Why do kids who are healthy, active, and eating well need to be
Vaccinations are intended to help
healthy kids healthy. Because vaccines work by protecting the body
before disease strikes, if you wait until your child gets sick, it
will be too late for the vaccine to work. The best time to immunize
kids is when they're healthy.
Can immunizations cause a bad reaction in my child?
The most common reactions to vaccines are minor and include:
- redness and swelling where the shot was given
- soreness at the site where the shot was given
In rare cases, immunizations can trigger more serious problems,
such as seizures or severe allergic reactions. If your child has a
history of allergies to food or medication, or has had a problem
with a vaccine previously, make sure to let the doctor know before
any vaccines are given. Every year, millions of kids are safely
vaccinated and almost all of them experience no significant side
Meanwhile, research continually improves the safety of
immunizations. The American Academy of Pediatrics (AAP) now advises
doctors to use a diphtheria,
, and pertussis vaccine that includes only specific parts of the
pertussis cell instead of the entire killed cell. This vaccine,
called DTaP, has been associated with even fewer side
Do immunizations or thimerosal cause autism?
Numerous studies have found no link between vaccines and
(a developmental disorder that's characterized by mild to
severe impairment of communication and social interaction skills).
Likewise, a groundbreaking 2004 report from the Institute of
Medicine (IOM) found that
(an organic mercury compound that's been used as a preservative
in vaccines since the 1930s) does
cause autism. Still, some parents have opted not to have their
children immunized, putting them at great risk of contracting
The MMR vaccine, especially, has come under fire despite many
scientific reports indicating that there's
no clear evidence
linking the vaccine to autism. In fact, in 2004 a long-disputed
1998 study that suggested a possible link between autism and the
MMR vaccine was retracted. Even before the retraction, not only had
other studies found
, but the controversial 1998 study was rejected by all major health
organizations, including the AAP, the National Institutes of Health
(NIH), the Centers for Disease Control and Prevention (CDC), and
the World Health Organization (WHO).
There's also no reason to believe that thimerosal is linked
to autism, according to the 2004 IOM report. Nevertheless, in an
effort to reduce childhood exposure to mercury and other heavy
metals, thimerosal began being removed from kids' vaccines in
1999. Now, vaccines for infants and young children contain no or
very little thimerosal. And recent studies have
cognitive and behavioral problems in babies who might have received
these thimerosal-containing vaccines.
So what could explain the increased rates of autism in recent
years? For one thing, there's a broader definition of autism
that can be applied to more kids who show varying degrees of
symptoms. A greater awareness of the condition among health
professionals also has led to more diagnoses.
And although the number of children diagnosed with autism may be
increasing, the rates of MMR vaccination are not. In London,
diagnoses of autistic disorders have been on the rise since 1979
but rates of MMR vaccination haven't increased since routine
MMR vaccination began in 1988.
In addition, the average age of diagnosis of autism has been
found to be the same both in children who have
who have not received the MMR vaccine. What many researchers are
discovering is that subtle symptoms of autism are often present
before a child's first birthday - sometimes even in early
infancy - but often go unnoticed until the symptoms are more
obvious to parents.
Wasn't there a problem with the rotavirus vaccine?
is one of the most common causes of diarrhea in young children. In
1999, a rotavirus vaccine was taken off the market because it was
linked to an increased risk for intussusception, a type of bowel
obstruction, in young infants. However, a new, different rotavirus
vaccine called RotaTeq became available in 2006 and has not been
found to have this increased risk. RotaTeq has been shown to
prevent approximately 75% of cases of rotavirus infection and 98%
of severe cases. The vaccine is now on the regular immunization
schedule to be given orally to infants as a liquid during standard
vaccination visits at ages 2 months, 4 months, and 6 months. Your
doctor will have the most current information.
Do immunizations cause SIDS, multiple sclerosis, or other
There are concerns, many of which circulate on the Internet,
linking some vaccines to multiple sclerosis, sudden infant death
syndrome (SIDS), and other problems. To date, several studies have
connection between immunizations and these conditions. The number
of SIDS cases has actually fallen by more than 50% in recent
years, whereas the number of vaccines administered yearly has
continued to rise.
Why does my child need to be immunized if the disease has been
Diseases that are rare or nonexistent in the United States, like
measles and polio, still exist in other parts of the world. Doctors
continue to vaccinate against them because it's easy to come
into contact with illnesses through travel. That includes anyone
who may not be properly immunized who's coming into the United
States, as well as Americans traveling overseas.
If immunization rates fell, a disease introduced by someone
visiting from another country could cause serious damage in an
unprotected population. In 1994, polio was brought to Canada from
India, but it didn't spread because so many people had been
immunized. It's only safe to stop vaccinations for a particular
disease when that disease has been eradicated worldwide, as in the
case of smallpox.
How long does immunity last after getting a vaccine?
A few vaccines, like the two for measles or the series for
B, may make you immune for your entire life. Others, like tetanus,
last for many years but require periodic shots (boosters) for
continued protection against the disease.
The whooping cough (pertussis) vaccine also does
give lifelong immunity, and that may be one reason why there are
still outbreaks of the disease. And although pertussis isn't a
serious problem for older kids and adults, it can be for infants
and young children. Because of this, adolescents and adults now
receive a pertussis booster along with the tetanus and
diphtheria booster (Tdap) - an important step in controlling this
It's important to keep a record of vaccinations so the
doctor knows when your child is due for a booster. Also make
sure your child gets the
each year, if it isn't in short supply. Having been
immunized last year won't protect someone from
getting the flu this year because the protection wears off and flu
viruses constantly change. That's why the vaccine is updated
each year to include the most current strains of the virus.
The flu vaccine reduces the average person's chances of
catching the flu by up to 80% during the season. But because the
flu vaccine doesn't prevent infection by all of the viruses
that can cause flu-like symptoms, getting the vaccine isn't a
guarantee that someone won't get sick during the season. But
even if someone who's gotten the shot gets the flu, symptoms
will usually be fewer and milder.
Are vaccines continuously studied and improved because
The FDA's Center for Biologics Evaluation and Research is
the government agency responsible for regulating vaccines in the
United States. Working in conjunction with the CDC and the NIH,
they continuously research and monitor vaccine safety and
New vaccines are licensed only after thorough laboratory studies
and clinical trials, and safety monitoring continues even after a
vaccine has been approved. There have been - and will continue to
be - improvements (such as those that have already been made to the
DTaP and polio vaccines, for example) that will minimize potential
side effects and ensure the best possible safety standards.
Where can I get affordable immunizations for my child?
Clearly, vaccines are one of the best tools we have to keep kids
healthy, but the effectiveness of immunization programs depends on
availability. You can receive inexpensive or free vaccines through
many local public health clinics and community health centers, and
campaigns to vaccinate kids often hold free vaccination days.
A program called Vaccines for Children covers Medicaid-eligible,
uninsured, Alaskan and Native American populations, and some
underinsured kids for routine immunizations up to 18 years of age.
The vaccines are provided by the government and administered in the
doctor's office. However, the doctor's visit itself is
covered (unless the child has insurance, including Medicaid). But
some public health clinics may cover both the visit and the
Where can I find out more about immunizations?
Your Child's Immunizations
for details about each recommended immunization. Also, the
CDC's National Immunization Program maintains a website
dedicated to helping consumers evaluate information about
vaccinations from sources in the media and on the Internet.
And talk with your doctor about which immunizations your
child needs - working together, you can help keep your child
Larissa Hirsch, MD
Date reviewed: November 2008
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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