Barriers to measles and pertussis immunization: the knowledge and attitudes of Pennsylvania primary care physicians.

To understand the causes of low childhood immunization rates, physicians were interviewed about their knowledge, attitudes, and self-reported immunization practices. Trained interviewers conducted a standardized telephone survey of physicians. A random sample of Pennsylvania family physicians, pediatricians, and general practitioners younger than 65 years of age who were in office-based practices was selected from the combined listings of the American Medical Association and American Osteopathic Association. Physicians seeing > or = 5 patients per week under age 6 years, seeing a total of > or = 15 patients per week, and having > or = 50% primary care patients were eligible. Of 383 eligible physicians, 70% (268) responded. The questionnaire was designed using the Health Belief Model, immunization barriers, and input from practitioners in primary care, pediatric infectious disease, maternal/ child health, and preventive medicine. Respondents were more likely to refer to public vaccine clinics those children without insurance (P < .001) or with Medicaid (P < .001) than children with insurance. Almost all (> 90%) respondents thought that vaccine efficacy was high and that the likelihood of serious side effects was low. However, only 37% gave estimates that corresponded with the literature regarding the likelihood of an infant with pertussis to need hospitalization. Many respondents used invalid vaccine contraindications; for instance, 37% would not administer MMR to a boy whose mother was pregnant. Many respondents (21%) would not administer four vaccines simultaneously. If the Healthy People 2000 goal to eliminate indigenous cases of measles is to be achieved, free vaccine supplies and increased provider education are needed.