Several reasons argue against alternative vaccine schedules. First, the current immunization schedule is designed to protect children against diseases when they are most susceptible; delay prolongs susceptibility to infection. It is impossible for parents, pediatricians, or authors of published alternative immunization schedules to predict when a child will come into contact with a vaccine-preventable disease. Second, the concern that vaccines may overwhelm the immune system is not science-based. From the moment of birth, infants are bombarded with microbes from the maternal genitourinary tract and the environment that challenge the developing immune system. The additional antigenic exposure from vaccines pales in comparison. In fact, the neonatal immune system theoretically could respond to up to 10,000 vaccines at a time. (9) Furthermore, although the number of childhood immunizations has increased over the past 2 decades, the total antigenic burden from vaccines has decreased, largely due to discontinuation of whole-cell pertussis vaccines. Finally, several studies have demonstrated that children who receive their vaccines on time are no more likely to develop autism or neurodevelopmental delay than children whose vaccine receipt is delayed.