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Immunizations and Screenings

Regular health exams and tests can help find problems before they start. They also can help find problems early, when chances for treatment and cure are better. By getting the right health services, screenings, and treatments, people can take steps to help their chances for living a longer, healthier life.

Immunization is the process whereby a person is made immune or resistant to an infectious disease, typically by the administration of a vaccine. Vaccines stimulate the body's own immune system to protect the person against subsequent infection or disease. The US Centers for Disease Control and Prevention (CDC) recommends routine vaccination to prevent vaccine-preventable diseases that occur in infants, children, adolescents, and adults.

Screenings are medical tests that doctors use to check for certain disorders before there are any symptoms. Screenings help find disorders earlier, when they may be easier to treat.

Preventive services are key to reducing death and disability and improving the nation's health. These services both prevent and detect illnesses and diseases - from flu to cancer - in their earlier, more treatable stages, significantly reducing the risk of illness, disability, early death, and medical care costs. Yet, despite the fact that these services are covered by Medicare, Medicaid, and many private insurance plans under the Affordable Care Act, millions of children, adolescents, and adults go without clinical preventive services that could protect them from developing a number of serious diseases or help them treat certain health conditions before they worsen. Increasing the number of people who take advantage of and have access to clinical preventive services continues to be a major public health challenge.

Immunization is a proven tool for controlling and eliminating life-threatening infectious diseases and is estimated to avert between 2 and 3 million deaths each year. 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; it can be delivered effectively through outreach activities; and vaccination does not require any major lifestyle change. Immunization directly protects individuals who receive vaccines and herd (community) immunity prevents the spread of infection in the community by indirectly protecting those who can't get vaccinated for certain diseases, such as people with some serious allergies and those with weakened or failing immune systems (like people who have cancer, HIV/AIDS, type 1 diabetes, or other health conditions). Community immunity is also important for the very small group of people who don't have a strong immune response from vaccines.
  • 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).

In 2017, U.S. national vaccination coverage among children aged 19-35 months was:
  • 83.2% for ≥ 4 doses of Diphtheria, Tetanus, and Acellular Pertussis (DTaP) vaccine,
  • 92.7% for ≥ 3 doses of poliovirus vaccine,
  • 91.5% for ≥ 1 dose of Measles, Mumps, and Rubella (MMR) vaccine,
  • 91.4% for ≥ 3 doses of Hepatitis B (HepB) vaccine,
  • 80.7% for full series of Haemophilus influenenza type b conjugate vaccine (Hib),
    • (≥ 3 or ≥ 4 doses, depending on product type)
  • 91.0% for ≥ 1 dose of varicella (chickenpox) vaccine, and
  • 82.4% for ≥ 4 doses of pneumococcal conjugate vaccine (PPV).

Coverage with the combined vaccine series (4:3:1:3:3:1:4) (see above) was 70.4% in 2017.1

In 2017, U.S. national vaccination coverage among adolescents/teens aged 13-17 years was:
  • 88.7% for ≥ 1 dose of Tetanus, diphtheria and acellular pertussis (Tdap) vaccine,
  • 85.1% for ≥ 1 dose of meningococcal (MenACWY) vaccine,
  • 92.9% for ≥ 2 doses of Measles, Mumps, and Rubella (MMR) vaccine,
  • 68.6% for ≥ 1 dose of Human papillomavirus (HPV) vaccine among females,
  • 53.1% of females up-to-date for HPV vaccine, and
  • 44.3% of males up-to-date for HPV vaccine.2

In 2017, U.S. national vaccination coverage among adults aged 65 years and older was:
  • 75.3% for ≥ 1 dose of pneumococcal vaccine and
  • 60.3% for influenza vaccine in the past 12 months.3

1. Hill HA, Elam-Evans LD, Yankey D, Singleton JA, Kang Y. Vaccination Coverage Among Children Aged 19-35 Months - United States, 2017. MMWR Morb Mortal Wkly Rep 2018;67:1123-1128. DOI:
2. Walker TY, Elam-Evans LD, Yankey D, et al. National, Regional, State, and Selected Local Area Vaccination Coverage Among Adolescents Aged 13-17 Years - United States, 2017. MMWR Morb Mortal Wkly Rep 2018;67:909-917. DOI:
3. BRFSS, downloaded on 7/05/2019 from


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 US and of geographic clustering of refusals that may result in vaccine-preventable disease outbreaks. Communities with pockets of unvaccinated and under-vaccinated populations are at increased risk for outbreaks of vaccine-preventable diseases.

Several studies have shown that children who are under-vaccinated 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.


To help doctors and patients decide together whether a preventive service is right for a person's needs, the US Preventive Services Task Force develops recommendations based on a review of high-quality scientific evidence. Specific recommendations for screening for over 75 conditions can be found here.

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 as a whole in addition to the individual vaccinated person.

The Centers for Disease Control and Prevention (CDC) recommend routine immunization to prevent 17 vaccine-preventable diseases that occur in infants, children, adolescents and adults. In 2017, the Advisory Committee on Immunization Practices released General Best Practice Guidelines for Immunization. The Guidelines are organized into 10 documents that provide information for clinicians and other health care providers about concerns that commonly arise when vaccinating persons of all ages. The guidance is organized in the following 10 documents: 1) Timing and Spacing of Immunobiologics; 2) Contraindications and Precautions; 3) Preventing and Managing Adverse Reactions; 4) Vaccine Administration; 5) Storage and Handling of Immunobiologics; 6) Altered Immunocompetence; 7) Special Situations; 8) Vaccination Records; 9) Vaccination Programs; and 10) Vaccine Information Sources.

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Immunization coverage is tracked at the national and state levels primarily through two surveys:
  • National Immunization Surveys (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-for infants, teens, pregnant women and health care workers.
  • 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