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Notice to Readers: Shortage of Varicella and Measles, Mumps and Rubella Vaccines and Interim Recommendations from the Advisory Committee on Immunization Practices

A temporary shortage of varicella (VARIVAX®) and combined measles, mumps and rubella (MMR) (M-M-R II®) vaccines in the United States has resulted from two voluntary interruptions to manufacturing operations by Merck & Co., Inc., the only U.S. manufacturer of these products. 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 Good Manufacturing Practices inspection. The other was the result of scheduled modifications made to the manufacturer's facility, which took longer than expected to be completed and had a substantial impact on production during September--October 2001. Following the interruptions of production, vaccine supply rapidly declined at the end of 2001.

Varicella Vaccine

Although the duration of the varicella vaccine shortage is uncertain, Merck predicts that the shortage will be resolved by late spring or early summer 2002. The annual need for varicella vaccine in the United States is about 6 to 7 million doses or 500,000--583,000 doses per month. Because of supply decreases, by March 4, approximately 1.1 million doses were on back order for both public and private sectors. Merck estimates an average of 60 days to fill these orders. Meanwhile, shortages are expected nationwide.

Interim ACIP Recommendations for Use of Varicella Vaccine

Varicella is a more severe disease among adolescents and adults; however, the highest incidence of disease is among elementary school aged-children (1,2). Until adequate supplies of varicella vaccine are available, ACIP recommends that all vaccine providers in the United States delay administration of the routine childhood varicella vaccine dose from age 12--18 months until age 18--24 months (3,4). If the shortage persists after delaying the dose at age 12--18 months and is of sufficient severity that further prioritization of vaccine use is needed, recommendations for use (highest to lowest priority) of Varivax® for susceptible persons are:

  1. Vaccination of health-care workers, family contacts of immuocompromised persons, adolescents aged >13 years, and adults and high-risk children (e.g., children infected with human immunodeficiency virus and children with asthma or eczema).
  2. Vaccination of susceptible children aged 5--12 years, particularly children entering school and adolescents aged 11--12 years. States may elect to provide guidance on priority cohorts for vaccination.
  3. Vaccination of children aged 2--4 years. Within this age group, states may elect to provide guidance on priorities (e.g., children attending child care centers) for vaccination.

Measles, Mumps and Rubella Vaccine

Although the duration of the shortage is uncertain, the manufacturer predicts that problems with the MMR vaccine supply should be resolved in 1--3 months. The annual need for MMR vaccine in the United States is about 13 million doses. The average number of MMR doses shipped during January--September 2001 was 943,000 doses; during October--November 2001, an average of 586,000 doses was shipped; during December 2001--February 2002, an average of 819,000 doses was shipped each month. As of March 4, a total of 1,077,670 doses was on back order for both the public and private sectors. As of February 28, 2002, the manufacturer projects that 5.6 million doses will be supplied during March--May 2002.

Interim ACIP Recommendation for Use of MMR Vaccine

Two doses of MMR vaccine, separated by at least a month and administered on or after the first birthday, are recommended for children, adolescents, and adults who lack adequate documentation of vaccination or other acceptable evidence of immunity (5). The first dose is recommended at age 12--15 months and the second dose at age 4--6 years. If providers are unable to obtain sufficient amounts of MMR vaccine to implement fully ACIP recommendations for MMR vaccination, ACIP recommends that they defer the second MMR dose. Because of the severity of measles in young children, providers should not delay administration of the first dose of the MMR series.

Tracking and Recall

Records should be maintained for children who experience a delay in administration of either varicella or MMR vaccines so they can be recalled when vaccine becomes available. The latest information about vaccine supply issues is available at


  1. Seward JF, Watson BM, Peterson CL, et al. Varicella disease after introduction of varicella vaccine in the United States, 1995--2000. JAMA 2002;287:606--11.
  2. Meyer P, Seward J, Jumaan A, Wharton M. Varicella mortality: trends before vaccine licensure in the United States, 1970--1994. J Infect Dis 2000;182:383--90.
  3. CDC. Prevention of varicella: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1996;45(No. RR11).
  4. CDC. Prevention of varicella: update recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1999;48(No.RR6).
  5. CDC. Measles, mumps, and rubella---vaccine use and strategies for elimination of measles, rubella, and congenital rubella syndrome and control of mumps: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1998;49:(No RR-8).

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