In recent years, the number of vaccine manufacturers has fallen (there are now only four pediatric vaccine
manufacturers that provide vaccine in the United States); many vaccines are produced by only one
manufacturer; and there have been periodic global shortages of routine vaccines. The reasons are complex for
the declining numbers of vaccine manufacturers and the rising potential for vaccine shortages. They include
high facilities and validation costs, limited profit margins, unstable pricing constructs for multivalent
vaccine, unpredictability in the annual pediatric immunization schedule; the complexity and long time frames
for regulatory approval/reapproval of facilities and processes; and shortages of well-trained personnel.