Voluntarily Reported Immunization Registry Data: Reliability and Feasibility to Predict Immunization Rates, San Diego, California, 2013.

Objectives: Accurate data on immunization coverage levels are essential to public health program planning. Reliability of coverage estimates derived from immunization information systems (IISs) in states where immunization reporting by medical providers is not mandated by the state may be compromised by low rates of participation. To overcome this problem, data on coverage rates are often acquired through random-digit-dial telephone surveys, which require substantial time and resources.