Vaccines have been a lifesaving public health measure since 1000 CE, when the Chinese first used smallpox inoculations to induce immunity.1 Work by pioneers such as Edward Jenner, Louis Pasteur, and Maurice Hilleman has averted countless millions of vaccine-preventable illnesses and deaths, and vaccines have become a routine part of health maintenance throughout the human life cycle.
Pregnant patients who receive vaccines often have an added benefit of protection provided to their infants through passive transfer of antibodies. Several vaccine platforms have been utilized in pregnancy with well-documented improvements in maternal and obstetric outcomes as well as improved neonatal outcomes in the first several months of life.
Risks of COVID-19 in pregnancy
The COVID-19 pandemic placed a spotlight on medically at-risk groups. Pregnant women are 3 times more likely to require admission to the intensive care unit, have increased requirement for extracorporeal membrane oxygenation treatment, and are up to 70% more likely to die than nonpregnant peers—and this risk increases with the presence of additional comorbidities.
In the case of COVID-19, vaccination trials that have shaped worldwide clinical practice unfortunately followed the historical trend of excluding pregnant patients from participation. This has required clinicians to guide their patients through the decision of whether or not to accept vaccination without having the same reassurances regarding safety and effectiveness afforded to their nonpregnant counterparts. With more than 86,000 pregnant women infected with COVID-19 through April 19, 2021, this lack of information regarding vaccine safety in pregnancy is a significant public health gap.2
COVID-19 vaccines
The current COVID-19 vaccines approved for use in the United States under an Emergency Use Authorization issued by the US Food and Drug Administration are nonreplicating and thus cannot cause infection in the mother or fetus. These are the Pfizer-BioNTech mRNA vaccine, the Moderna mRNA-1273 vaccine, and the Janssen Biotech Inc. monovalent vaccine. Furthermore, in animal studies that included the Pfizer-BioNTech, Moderna, or Janssen COVID-19 vaccines, no fetal, embryonal, female reproductive, or postnatal development safety concerns were demonstrated.
As of April 19, 2021, 94,335 pregnant women had received a COVID-19 vaccination, and 4,622 of these enrolled in the Centers for Disease Control and Prevention’s (CDC) V-safe Vaccine Pregnancy Registry.3 The data reported noted no unexpected pregnancy or infant outcomes related to COVID-19 vaccination in pregnancy. Adverse effects of the vaccine were similar to those in nonpregnant cohorts. Additionally, emerging data suggest passage of immunity to neonates, with maternal antibodies demonstrated in cord blood at time of delivery as well as in breast milk.4 To date, these data mainly have come from women immunized with the Moderna and Pfizer-BioNTech mRNA vaccines.
Counseling pregnant patients
Our counseling aligns with that of the American College of Obstetricians and Gynecologists, the Society for Maternal-Fetal Medicine, and the CDC’s Advisory Committee on Immunization Practices in that COVID-19 vaccination should not be withheld from pregnant patients or patients who want to become pregnant. In pregnant patients with comorbidities that place them at higher risk for severe COVID-19 infection, all available formulations of the COVID-19 vaccination should be strongly considered.
As evidence for vaccination safety continues to emerge, patients should continue to discuss their individual needs for vaccination in a shared decision-making format with their obstetric providers.