Missed opportunities to improve immunization status among high-risk children in the WIC program.

An investigation of a recent pertussis outbreak in Idaho showed that WIC participants were less well immunized than non-WIC participants. Conducting immunization status assessment and referral to a provider for vaccination (A/R) in WIC has been shown to significantly improve immunization. WIC files were abstracted to obtain immunization and visit histories. More frequent A/R at WIC has potential to improve the immunization status of preschool age WIC participants.