Supply Difficulties Expected with MMRV
Merck & Co., Inc. has notified the American Academy of Pediatrics and the Centers for Disease Control and Prevention (CDC) that, based on current market demand, the company projects the existing supply of ProQuad is likely to be depleted by July 2007. Once depleted, ProQuad is not expected to be available at least for the remainder of 2007.
Vaccine providers should begin transitioning from ProQuad to MMR and Varivax according to their current supply of vaccine.
In its April issue, AAP News reported that Merck (Whitehouse Station, N.J.) had temporarily suspended production of bulk varicella, which is used in the preparation of its three varicella-containing vaccines, due to lower than expected yields in recent production lots. Varicella bulk is stored frozen until it is needed in the final preparation phase of each varicella-containing vaccine. Thus, the lower virus yield in the production of bulk varicella zoster virus (VZV) does not affect the quality of any of Merck’s VZV-containing vaccines currently on the market, nor does it affect any lots of vaccine manufactured and ready for release to the market. Production of VZV bulk will remain suspended until Merck identifies the cause of the lower-than-expected virus yield.
To conserve existing bulk, Merck prioritized continued production of Varivax and the newly licensed zoster vaccine (Zostavax) over ProQuad, since production of Varivax requires less bulk varicella than does production of ProQuad. Zostavax is licensed for use in adults age 60 and older, and should never be administered to children.
Merck said it foresees no problems in meeting an increased demand for Varivax and MMR while ProQuad is unavailable. Further information is available in the CDC’s Morbidity and Mortality Weekly Report ( http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5618a6.htm ).
Supplies of Varivax are expected to be adequate for implementation of the new recommendation from the Academy and the CDC that a second dose of varicella vaccine routinely be administered to all children and adolescents without evidence of immunity to varicella-zoster virus.
Although the Academy recommends that the second dose of varicella-containing vaccine be administered routinely at 4-6 years of age, during the ProQuad shortage physicians who wish to reduce the number of injections at the 4-6 year old visit may routinely give the second dose of Varivax prior to this age, as long as the first and second doses are separated by at least 28 days (and preferably by at least three months). Full recommendations on use of varicella vaccine in pediatric patients are available online on the AAP Member Center, and will be published in the July issue of Pediatrics.
Questions about the supply of these Merck products can be addressed by contacting Merck’s National Service Center at 1-800-637-2590.
Updates on vaccine shortages and delays are available at: