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How Immunizations Work
Immunity is produced when your body is exposed to a weakened or killed virus or bacteria responsible for a particular disease. Once exposed, your body is able to recognize and produce antibodies quickly to fight off that type of infection in the future. Some vaccines give lifetime immunity, while others require periodic boosters.
There is little debate about the effectiveness of immunizations. Most doctors agree that the benefits of routine immunizations outweigh the risks. To ensure immunizations are up to date, keep a record. If you think you may be due for a booster or need a new vaccination, talk with your doctor.
Vaccine safety
Vaccines work best when as many people as possible receive them. The more people who are immunized, the lower the possibility of anyone being exposed to vaccine-preventable diseases. The United States currently has the safest, most effective vaccine supply in history. By law, years of testing are required before a vaccine can be licensed. Once in use, vaccines are continually monitored for safety and efficacy. The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) continually work to make already safe vaccines even safer.
Park Nicollet Health Services understands that vaccine safety is an ongoing concern for parents. The following information is to help parents and caregivers understand some of the common issues and questions surrounding this topic.
Thimerosal and autism
Thimerosal is a mercury-containing preservative that has been used since the 1930s to prevent contamination in multi-dose vials of vaccines. There is no convincing evidence of harm caused by the low doses of thimerosal in vaccines, except for minor reactions like redness and swelling at the injection site. However, in July 1999 the Public Health Service agencies, the American Academy of Pediatrics and vaccine manufacturers agreed that thimerosal should be reduced or eliminated in vaccines as a precautionary measure. Since 2001, with the exception of some influenza vaccines, thimerosal is not used as a preservative in childhood vaccines. The American Academy of Pediatrics, the American Medical Association, the CDC and the Institute of Medicine agree that scientific research does not support a link between thimerosal in vaccines and autism.
Measles, mumps and rubella (MMR) vaccine and autism
In 1998 a study of autistic children raised the question of a connection between MMR vaccine and autism. The 1998 study has a number of limitations. For example, the study was very small, involving only 12 children. This is too few cases to make any generalizations about the causes of autism. In addition the researchers suggested that MMR vaccination caused bowel problems in the children, which then led to autism. However, in some of the children studied, symptoms of autism appeared before symptoms of bowel disease. In 2004 ten of the 13 authors of the 1998 study retracted the study's interpretation. The authors stated that the data did not establish a causal link between the MMR vaccine and autism. There is no published scientific evidence showing that there is any benefit from separating the combination MMR vaccine into three individual shots.
In 2004 a report by the Institute of Medicine concluded that there is no association between autism and the MMR vaccine or vaccines that contain thimerosal as a preservative.
Web resources
How to identify reliable sources of immunization information on the Internet
General information on vaccines
General information on vaccine safety
Information on thimerosal and autism
Information on MMR and autism
Diphtheria/Tetanus/Pertussis
The diphtheria/tetanus/pertussis (DTaP) shot combines all three vaccines to protect against these life-threatening diseases. Most children should have five DTaP shots before they enter kindergarten. DTaP is a safer version of the older DTP shot. DTP is no longer used in the United States. DTaP is not given to children over the age of 7. Older children, teenagers, and adults need a booster shot called tetanus/diphtheria (Td).
Tetanus/Diphtheria
The tetanus/diphtheria booster shot is recommended at 11 to 12 years of age and then every 10 years. If you have a cut or wound that is caused by a dirty object, your doctor may recommend you have a tetanus booster even though you are up to date on your shot.
Polio
Since becoming available in the 1950s, the polio vaccine has nearly wiped out polio. However, the vaccination continues to be important, so this crippling and fatal disease does not return. Children should get this vaccine in a series of four doses. The polio vaccine can be taken orally or given by injection. In the United States the oral form is no longer available.
Haemophilus Influenza Type B
Haemophilus influenza type B (Hib) is a dangerous bacterium that can cause meningitis, pneumonia, and infections in other parts of the body. The Hib vaccine protects almost all children who receive the full four doses. It is given by injection.
Measles/Mumps and Rubella
The measles/mumps and rubella (MMR) vaccine is given by injection in two doses. In most people, these two doses provide protection for life.
Hepatitis B
The hepatitis B virus (HBV) can cause inflammation to your liver. This vaccine is given by injection in three doses to children. The vaccine should also be offered to adults younger than 40 years of age if they have not been previously immunized.
Chicken Pox (Varicella)
The varicella vaccine is given to children between 12 and 18 months age. It can be given to anyone at any age if they have not had chicken pox. Chicken pox is a common childhood illness that can be serious in young infants and adults. People aged 13 years and older who have not had chicken pox should receive two doses of the vaccine 4 to 8 weeks apart. It is especially important for non-pregnant women of childbearing age to be vaccinated, to reduce the risk of transmitting chicken pox to their fetus if they become pregnant.
Pneumococcal (PCV 7)
The pneumococcal (PCV 7) conjugate vaccine offers protection from Streptococcus pneumoniae bacteria, which can cause serious illness in children younger than 2. It is given in four doses before 15 months of age.
Influenza Vaccine
The influenza vaccine is recommended for:
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All adults 50 years and older
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Anyone who has a chronic illness
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Children aged 6 months to 5 years
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Caregivers and families of people at risk
The vaccine is updated every year because the viruses that cause influenza change from year to year. You need to get an influenza shot every year to be protected.
Pneumococcal (PPV 23)
The pneumococcal vaccine (PPV23) is recommended for all adults 65 years and older. It protects against 23 types of pneumococcal bacteria. It offers protection within 2 to 3 weeks in most healthy adults. It is given by injection. A second dose may be required for people who are at high risk. The second dose should be given 5 or more years after the first one.
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