Merck Plans to Resume Bulk Varicella Production Soon

As Merck corrects a manufacturing error that resulted in subpotent varicella bulk ingredient for its combination measles, mumps, rubella (MMR) and chickenpox (varicella) vaccine ProQuad, the company anticipates resuming production of the bulk ingredient shortly, Merck CEO Dick Clark said during the firm’s earnings call last month.

ProQuad (MMR and varicella vaccine live) is no longer available for U.S. consumption, and the company is encouraging patients to be vaccinated with separate chickenpox and MMR vaccines, specifically Varivax (varicella virus vaccine live) and M-M-R II.

Merck said that it was currently in the process of determining the root cause of the subpotent bulk ingredient.

The subpotent batches were discovered earlier this year, and the problem was identified before production commenced. The company had other batches of bulk varicella that did meet specifications and was able to supply finished product up until mid-2007, the company said.

Production of other varicella-based vaccines, including Varivax and shingles vaccine Zostavax (zoster vaccine live), is not affected as they require less varicella bulk ingredient in the manufacturing process, the company said.

Although Merck expects to be able to meet the long-term demand for chickenpox vaccines, “it is too early to determine when new supplies of ProQuad will be available in 2008,” the company said.