Vaccination FAQs

Medical Author: Edmond A. Hooker, MD, DrPH
Medical Editor: Melissa Conrad Stöppler, MD

• Why do we need vaccines? What is immunization? What is immunity?
• How can I become immune (protected)?
• Are there different types of vaccines?
• Can I receive multiple vaccinations during one visit to the doctor?
• Are there any dangers to being immunized?
• What reactions are likely after an immunization?
• Who should not receive a vaccine?
• If I am pregnant, which vaccines can I receive?
• What are invalid reasons for postponing vaccination?
• Why do we keep giving vaccines if the numbers of cases of the vaccine preventable diseases are at a record low in the United States?
• Is there any financial help for people who have been injured by vaccines?
• I am a health-care worker. Is there anything different that I need to do compared with non-health-care workers?
• I am planning foreign travel. Do I need any additional vaccinations?
• Where can I find additional information on immunizations?

Why do we need vaccines? What is immunization? What is immunity?

Vaccines are medications that boost our ability to fight off certain diseases. Many of the vaccine-preventable diseases are highly contagious and even fatal in unimmunized individuals (Table 1). Prior to the development of vaccines, these diseases disabled or killed millions of children. Many people living in developed countries today do not appreciate the value of vaccines because the successful use of vaccines has almost eradicated many of these diseases. These diseases are still dangerous and can kill people who are not adequately immunized.

Immunization is the act of receiving a vaccine. Immunity is the ability of the body to recognize specific infecting organisms as foreign and thereby protect against them.

How can I become immune (protected)?

Immunity (protection) can occur one of two ways:

• The first way to become immune is by actually getting the natural disease. For many organisms, this confers immunity for life. When the person is exposed again to the organism, the immune system quickly reestablishes protection.



• The second way to become immune is through the use of a vaccine. The vaccine interacts with the immune system and creates the same protection as if the person had the natural infections. This is done without being exposed to the risks involved with getting the natural infection.

Suggested Reading by Our Doctors

• Flu Vaccine - Get the facts about influenza vaccine (flu shot) ingredients, side effects and vaccination effectiveness. Learn who should (children, pregnant women, elderly) and shouldn't get a flu shot.
• Shingles - Read about shingles symptoms (contagious rash), vaccine, causes (chickenpox [varicella] virus, stress), treatment, how it's transmitted and postherpetic neuralgia.
• Childhood Vaccination Schedule - Read our printable children's immunization schedule and learn about vaccines for kids (Hib, polio, DTaP, MMR, HPV, flu, chickenpox, meningitis, rotavirus, pneumonia, hepatitis A and B).

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