Breastfeeding and Mother’s Immunity During a Measles Outbreak

This is a sensitive issue and we ask that mothers direct their questions to their health care providers.   Many mothers have questions about whether her own immunity to measles will afford her baby or babies some immunity because she is breastfeeding.  The answer is, unfortunately, that it is very difficult to say.  Maternal immunity is dependent on many factors that result in her current blood titers (i.e. the concentration of her own vaccines or immunity currently in her body).

What we can say is that breastfeeding is a benefit and may provide small, passive immunity. However, breastfeeding will not act as a substitute for immunization.

Be aware that there are two measles, mumps, and rubella vaccines, both manufactured by Merck:  MMR-II and MMRV/ProQuad.  The MMRV/ProQuad contains an additional vaccine for varicella (chicken pox).  According to the package inserts, both vaccines are only intended for individuals 12 months and older.

The CDC recommends individuals receive 1-2 doses of the MMR vaccine over a lifetime.  If for some reason, you are considering a booster for yourself as a nursing mother, according to the CDC, AAP, and Infant Risk Center, the MMR vaccine should not be given to women who are pregnant, but is considered compatible with breastfeeding because they have concluded that potential benefit outweighs potential risks.

However, according to the manufacturer’s package inserts for both MMR-II and MMRV/ProQuad, there is risk of transmission of rubella through breast milk.  The following statement appears on page 5 of the package insert for MMR-II: “However, transmission of the rubella vaccine virus to infants via breast milk has been documented (see Nursing Mothers).” Page 6 states, “Nursing Mothers: It is not known whether measles or mumps vaccine virus is secreted in human milk. Recent studies have shown that lactating postpartum women immunized with live attenuated rubella vaccine may secrete the virus in breast milk and transmit it to breast-fed infants.{53} In the infants with serological evidence of rubella infection, none exhibited severe disease; however, one exhibited mild clinical illness typical of acquired rubella.{54,55} Caution should be exercised when M-M-R II is administered to a nursing woman.”

According to the package insert, MMRV/ProQuad should not be administered to nursing women (p. 15).

Citations and further information:

Measles Outbreak with a Baby at Home by Wendy Sue Swanson, MD, MBE of Seattle Children’s Hospital

Do Mom’s Vaccines Protect Her Breastfed Baby? from Kellymom

Package Insert from MMR-II, Merck Pharmaceuticals via (see page 6)

Package Insert from MMRV/ProQuad, Merck Pharmaceuticals via their website (see page 15)

Immunizations and Pregnancy: Before, During, and After from the CDC

Factors determining prevalence of maternal antibody to measles virus throughout infancy: a review. Cáceres VM1, Strebel PM, Sutter RW.  Clin Infect Dis. 2000 Jul;31(1):110-9. Epub 2000 Jul 25.

Infant Risk Center – (806)-352-2519, Monday – Friday 8am-5pm

CDC Immunization Schedules for Adults from the CDC