Can varicella (chickenpox) and MMR (measles, mumps, and rubella) vaccines be given one week apart?

MMR and Varicella Vaccine Administration Timing

Varicella and MMR vaccines should not be given one week apart. If not administered on the same day, these live virus vaccines should be separated by at least 4 weeks (28 days) to ensure optimal immune response. 1, 2

Scientific Rationale for Timing

• The immune response to one live-virus vaccine might be impaired if administered within 30 days of another live-virus vaccine, as demonstrated in clinical studies 1
• A study conducted in U.S. health maintenance organizations found that persons who received varicella vaccine less than 30 days after MMR vaccination had a 2.5-fold increased risk for varicella vaccine failure compared with those who received varicella vaccine before or more than 30 days after MMR 1
• To minimize potential interference between live vaccines, parenterally administered live vaccines not given on the same day should be administered at least 4 weeks apart 1, 2

Correct Administration Options

• Option 1: Simultaneous Administration - MMR and varicella vaccines can be safely administered at the same visit at separate injection sites with separate syringes 1

  • Simultaneous administration produces seroconversion rates and adverse reaction rates similar to those observed when vaccines are administered separately 3, 4
  • This approach is particularly important when there's concern that a patient might not return for subsequent vaccination 1

• Option 2: Separated Administration - If not given simultaneously, the vaccines should be separated by at least 4 weeks (28 days) 1, 2

  • If live vaccines are separated by less than 4 weeks, the vaccine administered second should not be counted as a valid dose 1
  • The invalid dose would need to be repeated at least 4 weeks after the invalid dose 1, 2

Clinical Implications of Improper Timing

• Administering varicella vaccine 1 week after MMR (or vice versa) may result in suboptimal immune response to the second vaccine 1, 5
• The Centers for Disease Control and Prevention (CDC) and Advisory Committee on Immunization Practices (ACIP) explicitly recommend against administering these vaccines less than 28 days apart unless given on the same day 2
• Inadequate spacing between live virus vaccines may necessitate revaccination, resulting in unnecessary additional injections 1

Important Exception

• This timing restriction applies only to live virus vaccines given by the parenteral route 1
• Inactivated vaccines can be administered either simultaneously or at any time before or after a different inactivated vaccine or live vaccine without concern for interference 1, 6

Documentation and Follow-up

• If parenterally administered live vaccines are separated by less than 4 weeks, the second vaccine dose should be repeated after at least 4 weeks have elapsed since the invalid dose 1
• Proper documentation of vaccination dates is essential to prevent unnecessary revaccination and ensure appropriate spacing 2

Summary of Best Practice

• For optimal immune response and to minimize the risk of vaccine failure, either:
  1. Administer MMR and varicella vaccines on the same day at different injection sites 1, 3, or
  2. Separate administration by at least 4 weeks (28 days) 1, 2
• One-week separation between these vaccines is not recommended and may compromise vaccine effectiveness 1, 5