IYI Logo

Indiana Department of Health County Immunization Rate Assessment


Each year, the Advisory Committee for Immunization Practices (ACIP) releases a recommended
immunization schedule for childhood vaccination. These recommendations are supported by the
Centers for Disease Control and Prevention (CDC). For each vaccine-preventable disease, there are
particular rules and guidelines in the administration of the vaccine that, if followed, result in the
optimal immune response in the patient. If these guidelines are not adhered to, in some cases, a
child may be left unprotected. This can include scenarios in which the child was administered a dose
of vaccine incorrectly (invalid dose) or those who never receive the vaccine at all.

ACIP recommends children age 19-35 months complete the 4:3:1:3:3:1:4 immunization series
comprised of at least four doses of diphtheria-tetanus-acellular pertussis (DTaP), at least three doses
of polio, at least one dose of measles-mumps-rubella (MMR), at least three doses of Haemophilus
influenzae B (Hib) depending on the brand used, at least three doses of hepatitis B, at least one
dose of varicella antigens and at least four doses of pneumococcal conjugate vaccine (PCV).

County-level vaccination coverage estimates are important, both because public health issues often
originate in small geographic areas and because certain public health actions are most effective at
the local level. With the use of the state immunization registry, Children and Hoosier Immunization
Registry Program (CHIRP), a methodology has been developed for assessing children by county for
completion of the entire ACIP-recommended childhood immunization series (4:3:1:3:3:1:4).

It is increasingly important to measure children for completion of the entire series of childhood
vaccines, rather than focusing on one antigen. In assessing the complete series, we can assist in
improving immunization rates for at least 10 different vaccine-preventable diseases in one measure.
Improving the rate of completion for the entire series of childhood vaccines in those age 19-35
months can protect children from diseases such as diphtheria, pertussis, tetanus, polio, measles,
mumps, rubella, varicella, pneumococcal disease and Haemophilus influenzae.

Providing a measure of how well protected children are in specific communities assists
immunization programs throughout the state to identify areas of greatest need and enable the
targeting of resources. This may result in improving immunization rates in Indiana, which ultimately
will help reduce the incidence of morbidity and mortality due to vaccine-preventable diseases.


Source: Indiana Department of Health. (2022). County Immunization Rate Assessment.