In early January 2021, the World Health Organization (WHO) recommended against pregnant women receiving the Pfizer/BioNTech experimental mRNA COVID-19 vaccine due to insufficient scientific data for that vulnerable population.1 On Jan. 26, the WHO recommended against pregnant women receiving the Moderna experimental mRNA COVID-19 vaccine, with WHO director of immunization Kate O’Brien being quoted by Reuters as stating, “There is no reason to think there could be a problem in pregnancy, we are just acknowledging the data is not there at the moment.”2 3 4
On Jan. 29, however, the WHO reversed its recommendation to align itself more closely with that of the U.S. Centers for Disease Control and Prevention (CDC), which recommends that women can choose to get mRNA COVID-19 vaccines during pregnancy.5 6 7 8 9 The current WHO guidelines still note that there is little data available to assess COVID-19 vaccine safety during pregnancy but state:
Nevertheless, based on what we know about this kind of vaccine, we don’t have any specific reason to believe there will be specific risks that would outweigh the benefits. For this reason, those pregnant women at high risk of exposure to SARS-CoV-2 (e.g. health workers) or who have comorbidities which add to their risk of severe disease, may be vaccinated in consultation with their health care provider.10
To date, no vaccine using mRNA technology has been officially licensed as safe for humans. Pregnant women were left out of the clinical trials for both the Moderna and Pfizer/BioNTech experimental COVID-19 vaccines. This decision was made despite a call from The American College of Obstetricians and Gynecologists (ACOG) and other medical trade groups to include some expectant mothers in various COVID-19 related trials.11
Lack of Drug and Vaccine Safety Data in Pregnant Women Not Unusual
Lack of drug and vaccine safety data on pregnant women from clinical trials is not unusual. Epidemiologist David Schwartz, PhD, observed:
You’re dealing with a tremendously altered human being. The maternal cardiovascular system is different, as well as the hemodynamics, the immunology and the pharmacodynamics.10
In addition to the altered physiological state of the expectant mother, assessing the effects on both the mother and the fetus presents a potential medical, ethical and liability challenge because vaccines and drugs pass through the placenta to the fetus.12
Government recommendations for use of drugs during pregnancy that have been historically deemed safe by the U.S. Food and Drug Administration (FDA) and not believed to cause harm to the developing fetus have, on occasion, been revised.13 One example is the anti-nausea drug thalidomide, which was used off-label as a morning sickness drug for pregnant women during the late-1950s and early-1960s. At the time, the drug was not approved by the FDA and was considered to be experimental and was still being tested in clinical trials, yet it was widely used in the U.S. and Europe. Despite thalidomide being an unapproved experimental drug, approximately 20,000 patients, including 207 women who were known to be pregnant, received the drug in the U.S.14
Thalidomide was later found to cause catastrophic birth defects after some babies born to mothers, who took the experimental anti-nausea drug during pregnancy, were born without arms and/or legs.
Pregnant Women A Vulnerable Population, Fever Should Be Avoided in First Trimester
The experimental Moderna and Pfizer COVID-19 vaccines (mRNA-1273 and BNT162b2) are being distributed in the U.S. after being given an Emergency Use Authorization (EUA) by the FDA, but they have not been officially licensed as safe and effective by the federal agency. Under the EUA mechanism, the FDA commissioner may allow unapproved medical products to be used in emergency situations during a declared public health emergency.
Clinical trials administering unlicensed drugs and vaccines to pregnant women also face the challenge of ethics surrounding experimental testing on what is considered a vulnerable population. Historically women, especially those of low income and women of color, have been subject to unethical clinical trials without proper informed consent.12 Such was the case with the initial birth control pills that were unethically tested on women in Puerto Rico in the 1950s.15
Recommendations issued by the American College of Obstetricians and Gynecologists (ACOG), and now WHO recommendations as well, state that, while the absolute risk for severe COVID-19 during pregnancy is low, the vaccines should not be withheld from pregnant women. According to ACOG, conversations between pregnant women and providers may be helpful and patients should have “access to available information about the safety and efficacy of the vaccine, including information about the data that are not available.”16
There are currently no guidelines for when it is best to vaccinate against COVID-19 during pregnancy. Sonja Rasmussen, MD, a professor in the department of pediatrics and epidemiology at the University of Florida, notes that one known side effect of the Moderna and Pfizer COVID-19 vaccines is fever. She cautions that fever is “important to avoid during pregnancy—especially in the first trimester, when fever is associated with an increased risk of birth defects.”12
Click here to view References:
1 World Health Organization. Who can take the Pfizer-BioNTech Covid-19 Vaccine? Jan. 8, 2021.
2 Nebehay S, Blamont M. WHO experts issue recommendations on Moderna COVID-19 vaccine. Reuters Jan 26, 2021.
3 Gray C. WHO has new recommendations for COVID-19 vaccine during pregnancy. KSTP.com Jan. 27, 2021.
4 Kent S. Pregnant women shouldn’t get the Moderna COVID vaccine for now, WHO says. NJ.com Jan. 27, 2021.
5 Farber M. Moderna’s COVID-19 vaccine now recommended for pregnant women, WHO says in guidance reversal. Fox News Jan. 29, 2021.
6 Jerusalem Post Staff. WHO reverses stance on pregnant women receiving COVID-19 vaccine. The Jerusalem Post Jan. 30, 2021.
7 Mandavilli A. Pregnant Women May Receive Covid Vaccines Safely, W.H.O. Says. The New York Times Jan. 29, 2021.
8 U.S. Centers for Disease Control and Prevention. Vaccination Considerations for People who are Pregnant or Breastfeeding. Jan. 7, 2021.
9 Parpia R. Pregnant Health Care Workers Can Get COVID-19 Vaccines Despite Lack of Safety Data Says CDC. The Vaccine Reaction Jan. 3, 2021.
10 WHO. The Moderna COVID-19 (mRNA-1273) vaccine: what you need to know. Jan. 26, 2021.
11 Taylor MM et al. Inclusion of pregnant women in COVID-19 treatment trials: a review and global call to action. The Lancet Dec. 16, 2020.
12 Lenharo M. Why COVID Vaccines Are Likely Safe for Pregnant People. Scientific American Feb. 2, 2021.
13 Searing L. NSAIDs should be avoided after 20th week of pregnancy, FDA warns. The Washington Post Oct. 26, 2020.
14 Fintel B, Samaras AT, Carias E. The Thalidomide Tragedy: Lessons for Drug Safety and Regulation. HELIX July 28, 2009.
15 American Experience. The Puerto Rico Pill Trials. PBS.
16 ACOG Immunization, Infectious Disease, and Public Health Preparedness Expert Work Group. Vaccinating Pregnant and Lactating Patients Against COVID-19. The American College of Obstetricians and Gynecologists Feb. 4, 2021.