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Immunization Safety FAQ

While no medical intervention is 100% safe and effective, all vaccines approved for use in the US have been extensively tested for safety and serious side effects are very rare. If you or your child gets one of these dangerous diseases that vaccines can prevent, the risk of the disease is far greater than the risk of a serious adverse reaction to the vaccine.

Below is a series of Frequently Asked Questions (FAQs) about vaccine safety.

 

 What is a vaccine?

Vaccines stimulate our bodies’ immune system to fight off diseases by exposing us to dead or weakened versions of the bacteria or viruses (germs) contained in the vaccine.  Because the germs are dead or weakened, they do not cause disease when they enter our bodies.

 Can vaccines overload my child's immune system?

 

A fully vaccinated child will receive as many as 23 separate vaccines by their 2nd birthday (not including oral doses of Rotavirus vaccine). While this may seem like a lot, a baby’s immune system can deal with numerous challenges at a time. In one study, it was estimated that at least 10,000 shots would need to be given at the same time to overload a child’s immune system.
 Do children still get these diseases?

 

Yes. Although many vaccine-preventable diseases are rare in the United States, in many areas of the world where vaccination programs are not available these diseases are still widespread. Vaccine-preventable diseases are just a plane trip away and can be spread by people traveling . Those who remain unvaccinated are especially susceptible; multiple outbreaks of preventable diseases have occurred recently in the United States due to people choosing not to be vaccinated.
 Is immunity better if it comes from a natural infection?

 

No. Diseases have the ability to cause serious permanent damage to individuals, even death. Vaccines give immunity without the complications or risk from disease.
 Are vaccines safe?

 

Vaccines go through a testing process similar to medicines. The process usually takes several years to complete before the FDA (Food and Drug Administration) approves the vaccine for use. Even after approval, vaccines are continuously monitored for safety. But vaccines, like medications, can cause some side effects including soreness at the injection site, swelling, fatigue, headache, and fever. In most cases, these side effects go away quickly. Rarely, side effects may be severe due to an allergic reaction or other undiagnosed condition. If your child has any allergies or has had severe reactions to prior vaccinations, it is very important to let the doctor or nurse giving the vaccine know. Some parents are concerned by things they have heard on TV or read on the internet about vaccines causing severe diseases like asthma, multiple sclerosis, autism or diabetes. Well-designed research has shown no relationship between these chronic diseases and vaccines.
 What about mercury in vaccines?

 

Mercury is a toxic metal that can be found in the environment in different forms. How mercury is attached to other chemicals can greatly affect the toxicity of the mercury in any given chemical. Thimerosal, a mercury containing chemical used as a preservative, has low toxicity when used in small amounts, as it is in vaccines. However, concern that even low levels of mercury toxicity might exceed safe levels in babies and pregnant women led to a withdrawal of Thimerosal from most childhood vaccines in 1999. There has never been any research proving that Thimerosal is linked to or causes autism or other chronic diseases. Only some flu vaccines and a few less commonly used vaccines still contain Thimerosal.
 What about autism?

 

In 1998, British doctors published a report of a group of eight children who had developed autism after receiving Measles-Mumps-Rubella (MMR) vaccine. This report was widely publicized and led to an increase in anti-vaccine groups. Since then, many of the doctors have withdrawn their support from the original British report and over twenty studies found no link between autism and having received MMR vaccine. A 2009 legal decision ruled that there was insufficient evidence linking autism to vaccines. In 2010, the journal that published the initial report retracted the article.
 What if I don't vaccinate my child?

 

The decision not to immunize a child involves serious health risks if your child is ever exposed to a vaccine preventable disease. In addition, children who are not vaccinated may be subject to certain legal restrictions in the event of a communicable disease outbreak, including home quarantine and/or exclusion from school and daycare.
 How effective are vaccines?

 

Historically, vaccines have been very successful at reducing or eradicating the occurrence of certain diseases in the United States. A table comparing the number of cases of disease before and after vaccines were made available is located in the immunization statistics portion of this website.
 Are these diseases really serious?

 

Yes, for some people the diseases can be very severe, which could lead to hospitalization or death. Complications of these diseases can include deafness, blindness, brain damage, sterility, or paralysis. Babies are extremely susceptible to many of these diseases because their bodies’ defenses against germs are not fully developed. This also prevents some vaccines from being given to infants until after their 1st birthday. Therefore, it is important for everyone to be vaccinated so they can prevent these diseases from circulating in the community.
 What side effects might my child experience?

 

The most typical side effects include a slight fever, drowsiness, and soreness at the injection site. Although extremely rare, vaccinations have been known to cause serious side effects. If you are concerned that your child may be experience an adverse reaction to the vaccine, please contact your medical provider.