What caused the varicella shortage?
The current shortages in vaccine production resulted from two voluntary interruptions to manufacturing operations by Merck & Co., Inc., the only U.S. manufacturer of the varicella vaccine. One interruption was attributed to modifications Merck made voluntarily in response to issues raised by the U.S. Food and Drug Administration (FDA) during a routine current Good Manufacturing Practices (GMP) inspection. The other was the result of scheduled modifications made to the manufacturer’s facility, which took longer than expected to be completed and substantially impacted production during September-October 2001.
