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A person can be made immune or resistant to an infectious disease, by the administration of a vaccine. Vaccines stimulate the body's own immune system to protect the person against subsequent infection or disease.

Why It's Important

Immunization is a proven tool for controlling and eliminating life-threatening infectious diseases. It is one of the most cost-effective health investments, with proven strategies that make it accessible to even the most hard-to-reach and vulnerable populations. It has clearly defined target groups and can be delivered effectively through outreach activities. Vaccines are vital to the public health goal of preventing infectious diseases. Immunization directly protects individuals who receive vaccines and herd (community) immunity prevents the spread of infection in the community by indirectly protecting:
  • Infants who are too young to be vaccinated;
  • People who cannot be vaccinated for medical reasons (i.e. immunocompromised individuals);
  • People who may not adequately respond to immunization (i.e. elderly persons)

What Is Known

The 2022 vaccination recommendations are as follows:

Infants and children (birth through 15 months):

  • 3 doses of Hepatitis B (HepB) vaccine
  • 2-3* doses of Rotavirus (RV) (*depending on the type of vaccine)
  • 4 doses of Diphtheria, Tetanus, and Acellular Pertussis (DTaP) vaccine
  • 3-4* doses of Haemophilus influenza B (Hib) vaccine (*depending on the type of vaccine)
  • 4 doses of Pneumococcal conjugate vaccine (PCV13)
  • 3 doses of inactivated Poliovirus (IPV) vaccine
  • 1 dose of Measles, mumps, and rubella (MMR) vaccine
  • 1 dose of Varicella (chickenpox) vaccine
  • Influenza vaccine (yearly)
  • 2 doses of Hepatitis A (HepA) vaccine (6 months apart, starting at age 12 mos.)

Among children 18 months to 18 years:

  • Hepatitis B (HepB) vaccine (3rd dose before age 19 months)
  • Inactivated Poliovirus (IPV) vaccine (4th dose)
  • Measles, mumps, and rubella (MMR) vaccine (2nd dose, age 4-6 years)
  • varicella (chickenpox) vaccine (2nd dose, age 4-6 years)
  • Hepatitis A (HepA) vaccine (2nd dose before age 2)
  • Tetanus, diphtheria, and acellular pertussis (Tdap) vaccine (5th dose ~ age 7)
  • Human papillomavirus (~ age 12)
  • 2 doses of Meningococcal vaccine
  • Influenza vaccine (yearly)

Among adults aged 19 years or older:

  • Influenza vaccine (yearly)
  • 1 dose of Tetanus, diphtheria, and acellular pertussis (Tdap or Td) vaccine
  • 1-2 doses of Measles, mumps, and rubella (MMR) vaccine (if born after 1957 or later)
  • 2 doses of Varicella (chickenpox) vaccine (if born after 1980 or later)
  • 2 doses of Shingles zoster recombinant vaccine
  • 2-3 doses of Human papillomavirus (27 through 45 years)
  • Pneumococcal vaccine (1 dose PCV15 followed by PPSV23 OR 1 dose PCV20 both before and after age 65)
  • 2-3 doses of Hepatitis A (HepA) vaccine (depending on indication)
  • 2-4 doses of Hepatitis B (HepB) vaccine (depending on indication)
  • 2-3 doses of Meningococcal vaccine
  • 1-3 doses of Haemophilus influenza B (Hib) vaccine (depending on indication)
Recommendations vary for people with compromised immune systems and others. Your medical provider will be able to tell you.

Who Is at Risk

Recent outbreaks of vaccine-preventable diseases show that even vaccinated people are at risk for disease if there is not adequate immunization coverage in the population. There is evidence of an increase in vaccine refusal in the U.S. and of geographic clustering of refusals that may result in vaccine-preventable disease outbreaks. Communities with pockets of unvaccinated and undervaccinated populations are at increased risk for outbreaks of vaccine-preventable diseases.

Several studies have shown that children who are undervaccinated are likely to have missed vaccinations because of factors related to the health care system or sociodemographic characteristics. Furthermore, children with nonmedical exemptions and exemptions from school immunization requirements are at increased risk for acquiring and transmitting vaccine-preventable diseases and can infect others who are too young to be vaccinated, cannot be vaccinated for medical reasons, or are vaccinated but do not have a sufficient immunologic response.

How To Reduce Risk

Clinicians and other health care providers play a crucial role in parental decision making with regards to immunization. Health care providers are cited by parents as the most frequent source of information about vaccination. Furthermore, policy interventions, such as immunization requirements for school entry, have contributed to high vaccine coverage and record lows in the levels of vaccine-preventable diseases. Herd immunity has also played an important role in reducing transmission of a number of vaccine-preventable diseases, thereby benefiting the community in addition to the individual vaccinated person.

In 2011, the Advisory Committee on Immunization Practices released 2011 General Recommendations on Immunization . The Recommendations include vaccination guidelines for infants, children, adolescents, and adults.

The Recommendations provide information for:

  1. Timing and Spacing of Immunobiologics;
  2. Contraindications and Precautions;
  3. Preventing and Managing Adverse Reactions;
  4. Reporting Vaccine Adverse Events;
  5. the National Vaccine Injury Compensation Program;
  6. Vaccine Administration
For more information, visit:

How It's Tracked

Immunization coverage is tracked at the national and state levels primarily through two surveys:

  • National Immunization Survey (NIS), U.S. Centers for Disease Control and Prevention, National Center for Immunizations and Respiratory Diseases (NCIRD) and National Center for Health Statistics (NCHS), Adolescent and Teen Health
  • Behavioral Risk Factor Surveillance System (BRFSS), U.S. Centers for Disease Control and Prevention, Office of Surveillance, Epidemiology, and Laboratory Services

For more information on tracking immunization objectives, please visit the Immunization and Infectious Diseases topic at