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Notice to Readers: Update on Supply of Vaccines Containing Varicella-Zoster Virus

In February 2007, CDC received notice from Merck & Co., Inc., that because of lower than expected amounts of varicella-zoster virus (VZV) in its recently manufactured bulk vaccine, Merck was prioritizing production of varicella (Varivax®) and zoster vaccines (Zostavax®) over production of MMR-V vaccine (ProQuad®) (1).

In May 2007, CDC received further notice from Merck that current projections of orders indicate ProQuad will be unavailable beginning in July 2007, although timing will depend on market demand. This might cause extended back orders for the next few months. After depletion of the existing supply, ProQuad is not expected to be available for the remainder of 2007. Merck is requesting that customers begin transitioning from ProQuad to M-M-R II® and Varivax at their earliest convenience.

Merck expects to continue to meet demands for Varivax and M-M-R II to fully implement the recommended immunization schedule. This will allow for continued use of varicella vaccine for all age groups, including the routine 2-dose schedule for children aged 12--15 months and 4--6 years, catch-up vaccination with the second dose for children or adolescents who received only 1 dose, and vaccination with 2 doses for other children, adolescents, and adults without evidence of immunity (2--4). For zoster vaccine, the supply of Zostavax is expected to be adequate for routine vaccination of adults aged >60 years (5).

Questions regarding the supply of these Merck products should be addressed to Merck's National Service Center at 800-637-2590. Updates on vaccine shortages and delays are available from CDC at


  1. CDC. Supply of vaccines containing varicella-zoster virus. MMWR 2007;56:146--7.
  2. CDC. Prevention of varicella: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1996;45 (No. RR-11).
  3. CDC. Prevention of varicella: updated recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1999; 48(No. RR-6).
  4. ACIP provisional recommendations for prevention of varicella. June 2006. Available at
  5. ACIP provisional recommendations for use of zoster vaccine. October 2006. Available at

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Date last reviewed: 5/10/2007


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