Adequacy of Well-Child Care and Immunization

To the Editor.  —We are concerned that the otherwise valuable study by Dr Mustin and colleagues¹ has been misinterpreted by the media and will be similarly misunderstood by others unaware of the limitations of secondary data analysis.Mustin et al¹ concluded that while most US infants have adequate well-child visits, many remain inadequately immunized. The authors defined adequate well-child visits as one prior to 3 months of age plus one between the ages of 3 and 6 months. They defined adequate immunization as receipt of three diphtheria and tetanus toxoids and pertussis (DTP) vaccines and two oral poliomyelitis vaccines (OPVs) by 6 months of age. Because three visits at least 4 weeks apart are required to administer these immunizations, by the authors' definitions many infants will be classified as having received adequate well-child visits, but will be inadequately immunized at 6 months of age. Furthermore, some of the