Summary: Immunizations are considered one of the leading public health achievements of the 20th century. Mandatory immunization programs have eradicated polio and smallpox in the United States and reduced the number of deaths from several childhood diseases, such as measles, to near zero. A consistent supply of many different vaccines is needed to support this effort. Recent childhood vaccine shortages have prompted federal authorities to recommend deferring some immunizations and have caused states to reduce immunization requirements. At the state and local levels, 49 state immunization programs reported rationing one or more vaccines. Shortages have also prompted most states to waive or change immunization requirements for school and day care programs so that children who have not received all mandatory immunizations could enroll. Many factors contributed to recent vaccine shortages, and while these have largely been resolved, the potential exists for future shortages. On the supply side, some manufacturers had production problems, causing them to fall below their expected output, while others discontinued making some vaccines altogether. On the demand side, one manufacturer could not keep pace with the greater-than-expected demand for a new recommended vaccine. Federal agencies and advisory committees are exploring ways to help stabilize the nation's vaccine supply, but few long-term solutions have emerged. One option--expanding vaccine stockpiles--is being widely considered as a short-term strategy to help cushion disruptions in vaccine supply. Stockpiles have been used successfully to help mitigate supply disruptions in the past.
