One of the conclusions of the article published in the April 1996 issue of the Archives and titled "Variation in Patient Charges for Vaccines and Well-Child Care"1 was that charges for wellchild care vary less than would be expected if calculated solely on vaccine costs to providers and cost of living figures for the states studied. The authors further suggested that primary care providers in Massachusetts, where most vaccines are distributed free, might be compensating for lower immunization service charges by increasing charges for preventive care.
Costs and charges for medical care services are influenced by many factors, and this study attempted to review some of them. However, because of complex and incomplete data and striking regional differences, the authors felt obliged to make many estimates, guesses, calculations, simulations, and sampling variations. It is clear, however, that there are also many other factors, including managed care forces, competition, community