August 31, 2016
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Vaccination FAQs (cont.)

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Are there different types of vaccines?

There are two major categories of vaccines.

  • The first category of vaccine is made from live viruses that have been "attenuated" or weakened so that they do not cause the disease (Table 2). Usually, any symptoms caused by the vaccine is milder than the natural disease. The attenuated viruses elicit a strong immune response as the virus is very close to the virus that causes the disease.
  • The second category of vaccine, inactivated vaccine, is produced by growing the bacterium or virus in culture and then inactivating it (killing it) by using heat or chemicals (Table 3). These vaccines cannot cause the disease, but allow the body to develop immunity. While these vaccines are safer, they do not produce protection as good as that from the live vaccines.
Table 2: Live attenuated vaccines
Yellow fever
Intranasal influenza
Oral polio
Oral typhoid
Table 3: Inactivated (killed) vaccines
Polio shot
Hepatitis A
Hepatitis B
Influenza shot
Acellular pertussis
Human papillomavirus
Typhoid shot
Haemophilus influenza type b

Can people receive multiple vaccinations during one visit to the doctor?

Simultaneous administration (vaccines given at the same visit but not in the same shot) of most commonly used vaccines does not decrease the response to the vaccines or increase the risk for adverse reactions. The simultaneous administration of vaccines was instituted to increase compliance with recommended immunization schedules. If people have to come back many times to get additional shots, there is an increased chance that they will not get all recommended vaccinations. In children, there are now a few combination shots that contain multiple vaccines in a single shot. Most of these are approved for use in adults, except Tdap (a three-vaccine combination) and one containing measles/mumps/rubella (MMR). There is an ongoing controversy in the public media about giving "too many" vaccines at one time to little children. Physicians, however, do not believe that children are at risk from "too many" vaccinations given at one time.

Medically Reviewed by a Doctor on 9/25/2015


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