8. Is the COVID-19 vaccine safe for pregnant or postpartum/lactating women?
On December 11, 2020, the US Food and Drug Administration (FDA) issued emergency use authorization (EUA) for the Pfizer-BioNtech mRNA vaccine (BNT 162b2) against COVID-19, for individuals aged 16 and older as a 2-dose series given 21 days apart. Among the more than 40,000 individuals in the trial that led to this EUA, vaccine efficacy was 95%.19 Adverse effects included fatigue and headache most commonly, with 16% of vaccine recipients experiencing fever after the second dose. Follow-up regarding safety is planned for 2 years by the manufacturer, in addition to safety monitoring by pre-existing national systems.
On December 18, 2020, the FDA announced EUA for Moderna’s mRNA-based vaccine, mRNA-1273, in men and women aged 18 and older. This is a 2-dose series given 28 days apart. The vaccine efficacy has been reported at 94.5%, with the most common adverse effects being injection site pain, tiredness, headache, muscle pain, chills, joint pain, swollen lymph nodes in the same arm as the injection, nausea and vomiting, and fever.20,21 The phase 3 trial is ongoing.
Despite the speed with which these effective vaccines were developed, it is important to note that all regulatory and safety steps mandated for the development of any vaccine were met for these two, as well as for other COVID-19 vaccinations that will similarly receive EUA from the FDA.
In the EUA for BNT 162b2, the specific language regarding pregnant and lactating women recommends that patients and providers have an individualized conversation about vaccination. In the data presented to the FDA for the Pfizer-BioNtech mRNA vaccine, a limited number of pregnant women received either the vaccine (12 women) or placebo (11 women), with no long-term follow-up data available to characterize either maternal or fetal benefits and risks. The mechanism of action of an mRNA vaccine is to induce the cytoplasmic machinery within cells to create the coronavirus spike protein, which then allows the body’s immune system to create antibodies against this protein and confer protection accordingly. While the above mechanism is not theorized to result in different outcomes or different efficacy, the safety for the pregnant woman and fetus are unknown. It is not believed that vaccination during lactation would cause any adverse outcomes to a neonate, and lactating women do not need to interrupt or discontinue breast milk production in order to receive the vaccine.
The American College of Obstetricians and Gynecologists (ACOG) released a Practice Advisory on December 13, 2020, regarding their recommendations.22 ACOG recommends that vaccines against COVID-19 not be withheld from pregnant or lactating women, if they might otherwise meet criteria for and have access to vaccination. Currently, the CDC’s Advisory Committee on Immunization Practices (ACIP) stated that health care workers and long-term care facility residents represent priority groups to vaccinate in the initial phases of vaccination, given limitations in supply.23 This recommendation is likely to be updated frequently as additional vaccines become available. Shared decision-making between patient and provider may help the patient to make the best decision for herself, but provider input is not required prior to a pregnant woman being vaccinated.
Additional animal data evaluating adverse effects on the reproductive system from developmental and reproductive toxicity (DART) studies for both mRNA vaccines should be available in the coming weeks, which may aid in the counseling of reproductive-aged women.
Vaccine trials to specifically enroll pregnant women are set to begin in early 2021, and more data will certainly inform the conversation between patient and provider regarding risks and benefits.
Conclusions
While the absolute risks of COVID-19 to mothers, fetuses, and neonates is low, pregnancy is a risk factor for severe disease. Many pregnant women with COVID-19 can be safely followed as outpatients via telemedicine, and supportive care is recommended. Inpatient care should be individualized. Pregnancy during the COVID-19 pandemic should be not be absolutely discouraged; instead, a conversation about risk mitigation should be undertaken. The COVID-19 vaccine is available to pregnant and lactating women, and the decision to choose vaccination in pregnancy is in the purview of the patient, in consultation with her physician. ●