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Vaccines: myths and facts

This fact sheet answers frequently asked questions about vaccines.

Learn about 8 different vaccine myths and facts.



Fact 1: Hand washing and clean water are important to stop the spread of many diseases. However, many infections can still spread regardless of how clean we are. Vaccination is essential to stop the spread of infectious diseases. If people are not vaccinated, uncommon diseases, such as measles, can come back.

Fact 2: Vaccines are very safe. Vaccines go through thorough testing for years before approval for public use. vaccine monitoring continues after public approval. The Vaccine Adverse Event Reporting System is a national program that monitors reactions to vaccines. The Vaccine Adverse Event Reporting System ensures that the benefits of vaccines far outnumber the risks. Most vaccine reactions are minor and temporary, such as a sore arm or mild fever. Serious health events due to vaccines are extremely rare.

Fact 3: There is no evidence that these vaccines cause SIDS. Ninety percent of SIDS cases occur before an infant reaches the age of 6 months. The rate of SIDS is highest between 1 and 4 months of age. Unfortunately, this is the age when children receive their DTaP and polio vaccines. SIDS deaths are co-incidental to vaccination. These deaths would occur with or without these vaccines. 

Fact 4: Many vaccine preventable diseases are uncommon in the United States. But, these diseases still exist in the rest of the world. Measles, for example, is still common in some countries in Europe, Asia, the Pacific, and Africa. In 2014, there was a large outbreak of measles at the Disneyland theme park in California. Unvaccinated people made up the majority of those who got measles. Measles is very contagious and spreads easily among unvaccinated people. Vaccines can protect us at home or when we are on vacation from diseases that we may not know are around us.

Fact 5: There is no evidence that simultaneous vaccines hurt a child's immune system. Children face daily exposure to hundreds of foreign substances that can cause an immune response. Offering multiple vaccines at once decreases the number of clinic visits. This saves time and money. Combined vaccination is also less painful to children. In the case of MMR, it means fewer injections.

Fact 6: Influenza is a serious disease. The flu affects hundreds of people in Boston each year. Pregnant women, small children, the elderly, and those with chronic conditions, are at higher risk for severe illness from flu. It is important for pregnant women to get the vaccine. Mothers need to protect their newborns since there is no vaccine for babies under six months of age. The vaccine protects against the 3-4 strains of flu expected to circulate in a particular year.

Fact 7: Some vaccines contain thimerosal. Thimerosal is an organic, mercury-containing compound used as a preservative. It is most often used in multi-dose vials. Studies show that thimerosal is safe, and the amount used in vaccines does not cause a health risk. 

Fact 8: No. There is no evidence to link vaccines and autism.

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