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 Healthy Steps with Immunizations
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More than two hundred years ago, Edward Jenner, a country physician
practicing in England, noted that milkmaids rarely suffered from
smallpox, a disease that was known to kill up to 40 percent of those
who contracted it. The milkmaids often did get cowpox, a related but
far less serious disease, and those who did, never became ill with
smallpox. In an experiment that was to prove a revelation, Jenner took
a few drops of fluid from a skin sore of a woman who had cowpox and
injected the fluid into the arm of a healthy young boy who had never
had cowpox or smallpox. Six weeks later, Jenner injected the boy with
fluid from a smallpox sore, but the boy remained free
of the dreaded smallpox. Dr. Jenner had discovered one of the
fundamental principles of immunization. He had used a relatively
harmless foreign substance to evoke an immune response that would
protect someone from a disease.
It took some time to convince people that the benefits of
vaccination outweigh the few risks. Today’s vaccines are far safer and
more protective than those early vaccines. As science advances, even
better vaccines are being developed to protect us from disease.
Disease prevention is the key to public health. Vaccines benefit,
in particular, the people who receive them, and in turn, those people
cannot spread disease to others who have not been vaccinated.
Infection cannot spread if it never gains a foothold. Infectious
diseases cause enormous suffering, strain the capabilities of our
health care system, and deplete financial resources. For the
individual, the health care provider, and in the interest of
conserving human and financial resources, it is always better to
prevent a disease than to treat it. Veterinary vaccines benefit
people, too. Some diseases, such as rabies, anthrax, certain types of
encephalitis, and Rift Valley fever, are readily transmissible from
animal species to humans. In many instances, livestock and pets are
vaccinated not only for their own health, but for that of their
owners. Many childhood diseases that were a normal part of growing up
just 50 years ago are now preventable. Measles, rubella (German
measles), mumps, pertussis, (whooping cough), and chickenpox were
almost unavoidable. Most people did not reach adulthood without their
families or circle of friends being touched by a serious illness or
death caused by an infectious disease. For the most part, children
suffered through the course of the disease and were left with
naturally acquired immunity, some school work to catch up on, and
perhaps a little pockmark somewhere on their skin. However, in some
cases, children died, or they were left with permanent loss of hearing
or sight or other tragic effects of serious infections.
Although most of us receive the great majority of our immunizations
during childhood, it is important to remember that vaccines are not
just for young children. Adolescents and adults should keep up-to-date
on tetanus and diphtheria immunizations. Adults, who have not had
diseases such as measles or chickenpox during childhood, or the
vaccines to prevent them, should consider being immunized. Ironically,
childhood diseases such as measles, mumps, and chickenpox can
be far more serious in adults. People who travel overseas should
determine, together with their physicians or at international travel
clinics, which vaccines would be appropriate based on their
destinations. Effective vaccines are available to prevent yellow
fever, polio, typhoid fever, hepatitis A, cholera, and other bacterial
and viral diseases that are more prevalent abroad than in the United
States. Each year, as we prepare for
winter and the flu season, many adults should consider the benefits of
the flu vaccine. In addition to flu vaccine, immunizations for
pneumococcal pneumonia, hepatitis A, and hepatitis B are recommended
for people who may be at risk.
As early as 2,500 years ago in Greece, some people understood
enough about contagious diseases to know that a person who had
recovered from plague would not get it again. Later, physicians
recognized that a person acquires immunity to many diseases in this
way. It is true that natural infection almost always causes better
immunity than vaccines. Whereas immunity from disease often follows a
single natural infection, immunity from vaccines usually occurs only
after several doses. However, the difference between vaccination and
natural infection is the price paid for immunity. The price paid for
immunity after natural infection might be pneumonia from chickenpox,
mental retardation from influenza, pneumonia from pneumococcus, birth
defects from rubella, liver cancer from hepatitis B virus, or death
from measles.
The purpose of a vaccine is to bring about active immunity by
provoking a response from a person’s immune system and creating a
memory within the immune system so that exposure to the active disease
agent will stimulate an already primed immune system to fight the
disease. Some vaccines are combinations that protect against several
diseases. Most of us are familiar with the DTP (diphtheria, tetanus,
pertussis) and MMR (measles, mumps, rubella) vaccines that children in
the United States receive. Scientists extensively test these
combination vaccines to make sure that none of the antigens detracts
from the immune priming effect of the others. Thus the vaccines can
provide triple protection, the recipients are spared extra needle
sticks, and the public health costs are reduced. Based on the
biological and chemical characteristics of the disease-causing agent
and on what type of immunity is desired, researchers begin to develop
one of the following types of vaccines. Vaccines can be produced from
1-inactivated (or killed), 2-live, attenuated (or weakened), or
3-synthetic (or laboratory-made) microbial materials.
One preservative contained in some vaccines is called thimerosal.
Thimerosal contains mercury. Several studies have shown that when
pregnant women ingest large quantities of mercury that are found in
heavily contaminated fish, the developing fetus may be affected and
later be found to have neurological disturbances. Recent studies by
the National Institutes of Health showed that the levels of mercury
contained in the blood of immunized children are similar to those in
unimmunized children. But the Centers for Disease Control and
Prevention and the American Academy of Pediatrics were concerned that,
although there was no evidence that thimerosal caused harm, vaccines
might be "perceived" as unsafe. So they recommended that thimerosal be
removed from vaccines. The result is that all routinely recommended
vaccines should be free of thimerosal since the Spring of 2001.
Because the signs of autism may appear in the second year of life,
at around the same time children receive certain vaccines (such as MMR),
some parents wonder whether vaccines might cause autism. But the vast
weight of medical and scientific evidence now strongly refutes the
finding of one British study that MMR caused autism in eight children.
There is no scientific evidence that MMR vaccine causes autism.
A wealth of evidence now confirms the fact that vaccines do not
cause diabetes. A recent study found that the immunization rates for
Haemophilus influenzae type b (Hib) vaccine or the hepatitis B vaccine
were the same in children with diabetes as in children without
diabetes Although the incidence of diabetes is increasing throughout
the world, the increase has occurred in countries with or without the
introduction of new vaccines.
The number of children with SIDS has dramatically decreased since
the hepatitis B vaccine was recommended for all infants. In fact,
since all newborns were first recommended to receive the hepatitis B
vaccine at birth, the incidence of SIDS has dramatically decreased,
not increased. The decline in the number of children with SIDS is not
because of the hepatitis B vaccine, but rather because of a change in
sleep position for infants recommended by the American Academy of
Pediatrics.
Although the cause or causes of multiple sclerosis are not known,
multiple sclerosis is not caused by the hepatitis B vaccine. A large,
carefully controlled study of about 238,000 nurses found that the risk
of multiple sclerosis was the same in those who received the hepatitis
B vaccine as in those who didn't receive the vaccine. Vaccines don't
exacerbate the symptoms of multiple sclerosis in people who already
have the disease. The average age of people with multiple sclerosis is
exactly the same now as it was before the hepatitis B vaccine was
first used in this country.
Because vaccines are given to people who are not sick, they are
held to the highest standards of safety. As a result, they are among
the safest things we put into our bodies.
All vaccines have possible side effects. Most side effects are
mild, such as pain or tenderness where the shot is given. But some
side effects of vaccines can be severe. For example, vaccines, like
all medicines, have been found to rarely cause a severe allergic
reaction called anaphylaxis. Symptoms of anaphylaxis can occur within
15 minutes of getting any vaccine and include hives, difficulty
breathing, and low blood pressure. Although the reaction can be
treated, it can also be quite frightening.
Unfortunately, choosing to avoid vaccines is simply a choice to
take a different risk. Unvaccinated individuals are at risk from many
diseases including meningitis caused by Hib, bloodstream infections
caused by pneumococcus, pneumonia caused by measles, deafness caused
by mumps, and liver cancer caused by hepatitis B virus.
When you compare the risk of vaccines and the risk of diseases,
vaccines are the safer choice.
Some adults incorrectly assume that the vaccines they received as
children will protect them for the rest of their lives. Generally this
is true, except that:
- Some adults were never vaccinated as children.
- Scientific discoveries are always being made, bringing vaccines
into our lives that were not around during our childhood.
- The immunity provided by some of the vaccines received in
childhood begins to fade over time.
- Adults become more susceptible to serious disease caused by
common infections as they age. (For example, flu, pneumococcus)
Vaccines needed for all Adults (unvaccinated, medical
conditions or compromised immune function)
Additional vaccines needed for those over the age of 50
Additional vaccines needed for those over the age of 65
Additional vaccines needed for all health-care workers of all ages
Additional vaccines needed for child-care center workers of all ages
The following chart provides a suggested timetable for children.
The child's doctor may choose a somewhat different schedule, but you
can generally count on the following vaccines at the ages indicated.
|
Birth |
2 months |
4 months |
6 months |
12 months |
15 months |
18 months |
4-6 years |
| HBV #1 |
DTaP #1 |
DTaP #2 |
DTaP #3 |
MMR#1 |
Hib #4 |
Polio #3 |
MMR #2 |
| |
Polio #1 |
Polio #2 |
Hib #3 |
Varicella |
HBV #3 |
DTaP #4 |
Polio #4 |
| |
Hib #1 |
Hib #2 |
PCV #3 |
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PCV #4 |
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DTaP #5 |
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HBV #2 |
PCV #2 |
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PCV #1 |
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HBV - Hepatitis B Virus
DTaP - Diptheria, Tetanus, and Pertussis
Hib - Haemophilus influenzae Type b
PCV - Pneumococcal
MMR - Measles, Mumps, Rubella
Comprehensive immunization recommendations from CDC are at:
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