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Vaccines That Require More Than One Dose

Many vaccines require more than one dose to achieve immunity.81 The number of doses needed to achieve that immunity threshold depends on the type of antigen within the vaccine (alive or not)- for more information about vaccine antigens refer to “Types of Vaccines” webpage within the toolkit.

Below are the different categories of vaccines: Click on the different categories to learn how many doses each specific vaccine requires to reach immunity. As a bonus, click on the specific vaccine preventable disease to read more regarding that vaccine preventable disease.

  • Inactivated vaccines use the “inactivated” version of the germ that causes a disease. Since it uses an “inactivated” germ type these vaccines may need several doses to reach immunity and some may also require more doses over time, referred to as booster shots, in order to gain ongoing immunity against that disease.


    Examples of Inactivated Vaccines:


    • DTaP/Tdap/Td130
      • Requires up to 6 initial doses130
      • Booster doses every 10 years130
      • Certain circumstances require additional doses (ex: pregnancy)- refer to Vaccines: Pregnant People webpage within the toolkit





    • Polio136
      • Requires up to 4 doses136




    • Meningococcal139
      • There are 3 types of meningococcal vaccines used in the United States. Each vaccine has its own recommendations for dosage. Due to the specific parameters for each vaccine and to ensure the latest information on recommended intervals for vaccinations, please visit the CDC- Meningococcal Vaccine: What everyone should know.
  • Live vaccines use a weakened (or attenuated) form of the germ that causes a disease. These vaccines are so similar to the natural infection that they help prevent, they create a strong and long-lasting immune response. Just 1 or 2 doses of most live vaccines can give a lifetime of protection against the germ that cause the vaccine preventable disease.

    Examples of Live-Attenuated Vaccines:

  • Seasonal vaccines are vaccines that require an initial round of vaccinations (up to 2 doses, depending on circumstance to reach immunity) as well as seasonal booster doses to protect against mutation-prone viruses that cause waves of infections months or years apart.

    Examples of Seasonal Vaccines:

    • Influenza140
      • Could require up to 2 doses of initial round of vaccine, based on age and health related circumstances. See CDC Flu vaccine schedule.141
      • Every year the seasonal flu vaccine is reformulated to target the four strains expected to be most problematic for that season.141
        • Everyone 6 months and older in the United States should get an influenza (flu) vaccine every season.140
    • COVID-1924
      • Dosing requirements are based on age and health related circumstances. Refer to CDC COVID-19 Vaccine Schedule for the most up to date information.24
      • Booster doses are based on fading immunity of current vaccine periods as well as fast-evolving virus protection24
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