ProQuad was licensed in 2005 for use in children ages 12 months through 12 years. It combines the measles-mumps-rubella (MMR) and varicella vaccines and therefore can be used in place of the individual MMR and varicella vaccines given at ages 12–15 months and 4–6 years. Because of an increased risk of febrile seizures when MMRV is administered as a first dose to children 12-23 months of age, the American Academy of Pediatrics (AAP) recommends that providers considering using MMRV in this age group should discuss the benefits and risks of vaccination options with parents or caregivers, and use MMRV in this situation when the informed parent or caregiver prefers this option. CDC recommends separate MMR and varicella vaccination for eligible children younger than age 4 years, unless the parent prefers MMRV. For more information, consult the package insert at www.merck.com/product/usa/pi_circulars/p/proquad/proquad_pi_4171.pdf.
Last reviewed:
August 12, 2026
Post-licensure studies of MMRV suggested that, during the 5–12 days after vaccination, approximately one additional febrile seizure occurred among every 2,600 children ages 12 through 23 months vaccinated with a first dose of MMRV vaccine compared with children in the same age group vaccinated with separate first doses of MMR vaccine and varicella vaccine administered during a single office visit.
For this reason, the recommendations for use of MMRV vaccine are as follows:
- The routinely recommended ages for measles, mumps, rubella, and varicella vaccination are age 12 through 15 months for the first dose and age 4 through 6 years for the second dose.
- The American Academy of Pediatrics (AAP) advises that for the first dose of measles, mumps, rubella, and varicella vaccines at age 12 through 23 months, providers may use either MMR vaccine and varicella vaccine or MMRV vaccine. Providers who are considering administering MMRV vaccine should discuss the benefits and risks of both vaccination options with the parents or caregivers. Unless the parent or caregiver expresses a preference for MMRV vaccine, CDC recommends that providers administer separate MMR vaccine and varicella vaccine for the first dose in eligible children younger than age 4 years.
- AAP recommends that MMRV is generally preferred for the second dose typically administered at age 4 through 6 years to reduce the number of injections needed. Historically, CDC has also stated that for the second dose of measles, mumps, rubella, and varicella vaccines at any age (15 months through 12 years) and for the first dose, if given at age 48 months and older, use of MMRV vaccine generally is preferred, if available, over separate injections of its equivalent component vaccines to reduce the number of injections (i.e., MMR vaccine and varicella vaccine).
- A personal or family (e.g., sibling or parent) history of seizures of any etiology (i.e., cause) is a precaution for MMRV vaccination, and such children generally should be vaccinated with MMR vaccine and varicella vaccine.
The complete original recommendations for the use of MMRV vaccine by ACIP in 2010 are available on CDC’s website at www.cdc.gov/mmwr/pdf/rr/rr5903.pdf.
The current AAP childhood immunization schedule is available on the Immunize.org website at: www.immunize.org/official-guidance/hpo/rec-schedules/.
Last reviewed:
August 12, 2026
Absolutely not. Vaccines should never be mixed except when specifically approved by FDA and packaged for that specific purpose.
Last reviewed:
August 12, 2026
Twelve weeks. The spacing between doses of a combination vaccine depends on the longest minimum interval of a component. The minimum interval between doses of MMR is 4 weeks; the minimum interval between doses of varicella vaccine is 12 weeks for a child this age. So, you should wait 12 weeks between the doses of MMRV for the two doses to be valid.
Last reviewed:
August 12, 2026
In the case of an expired live vaccine, the issue is not necessarily the routine minimum interval (three months in the case of varicella and ProQuad vaccines), but the interval that would prevent viral interference if the expired vaccine happened to be still viable. This interval is considered to be four weeks (28 days). The repeat dose should be administered four weeks after the expired dose.
Last reviewed:
August 12, 2026
Last reviewed:
May 23, 2023
Yes, however, this issue is not addressed in the 2010 MMRV ACIP recommendations. Although this is off-label use, CDC recommends that when a dose of MMRV is inadvertently given to a patient age 13 years or older, it may be counted towards completion of the MMR and varicella vaccine series and does not need to be repeated.
Last reviewed:
August 12, 2026
