COVID-19 mRNA (Moderna) vaccine Pregnancy and Breastfeeding Warnings

Brand names: Moderna COVID-19 Vaccine, Spikevax, mNEXSPIKE

Medically reviewed by Drugs.com. Last updated on Sep 6, 2024.

COVID-19 mRNA (Moderna) vaccine Pregnancy Warnings

Animal studies have failed to reveal evidence of fetal harm. A vaccine formulation containing 100 mcg of nucleoside-modified messenger RNA (mRNA) per dose (the same quantity of mRNA in a single primary series dose of Spikevax for patients 12 years and older) was administered IM to female rats on 4 occasions (twice prior to mating and twice during gestation); no vaccine-related fetal malformations/variations and no adverse effect on postnatal development were observed. There are no controlled data in human pregnancy.

To monitor the outcomes of pregnant women exposed to this vaccine, a pregnancy registry has been established. Women vaccinated during pregnancy are encouraged to enroll in the registry by visiting https://mothertobaby.org/ongoing-study/covid19-vaccines/.

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D, and X are being phased out.

The manufacturer makes no recommendation regarding use during pregnancy.

US FDA pregnancy category: Not assigned

Risk summary: Insufficient data are available on the use of this vaccine in pregnant women to inform a drug-related risk.

Comments:
-A pregnancy exposure registry is available.
-Compared with nonpregnant patients, the risk of severe COVID-19 is increased in pregnant patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

See references

COVID-19 mRNA (Moderna) vaccine Breastfeeding Warnings

Use is generally considered acceptable; benefit to mother should outweigh risk to the infant.

Excreted into human milk: Unknown
Excreted into animal milk: Data not available

Comments:
-Developmental and health benefits of breastfeeding should be considered as well as the mother's clinical need for this vaccine.
-The effects in the nursing infant are unknown; potential adverse effects in the breastfed child due to this vaccine or the mother's underlying condition should be considered.
---For preventative vaccines, the mother's underlying condition is susceptibility to disease prevented by the vaccine.
-Many experts recommend offering COVID-19 vaccines to those who are breastfeeding because the potential benefits of maternal vaccination during lactation outweigh any theoretical risks.

COVID-19 VACCINES:
Many studies have been reported that have involved hundreds of women who received a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)/COVID-19 vaccine and their infants. No evidence suggests receiving a vaccine against SARS-CoV-2 is harmful to either the nursing mother or the breastfed infant.

Antibodies and T-cells that neutralize the SARS-CoV-2 virus appear in the milk after maternal vaccination. Neutralizing capacity may increase even while antibody levels drop. Lactoferrin levels have also increased in milk after maternal vaccination. There is no plausible mechanism for intact, complete, functional viral S proteins from messenger RNA (mRNA) vaccines to be distributed into milk from maternal circulation after immunization. Testing of milk from mothers who received other mRNA vaccines found little to no mRNA in their milk.

Nursing mothers have reported minimal disruption of breastfeeding after vaccination, which may have been related to experiencing systemic symptoms. A few mothers reported blue or blue-green discoloration of their milk. A small percentage of breastfed infants have experienced sleepiness, increased fussiness, fever, rash, or self-limiting diarrhea, but no serious adverse effects have been reported.

See references

Further information

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