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School of Public Health Expert Insights

Pregnant woman in a mask

Will Coronavirus Vaccines Be Safe for Pregnant Women?

By Ruth Faden, Ruth Karron, and Carleigh Krubiner | August 21, 2020


Nearly 200 coronavirus vaccines are in development—with the hopes of eventually giving us a key tool to stem the COVID-19 pandemic.

But will new vaccines be safe to give to pregnant women?

Currently, pregnant women are not being enrolled in vaccine trials, but will they be in the future? How and when will evidence about a vaccine’s safety or risks for pregnant women and their offspring become available?

In this Q&A, Johns Hopkins experts Ruth Karron, Ruth Faden, and Carleigh Krubiner—leaders of the Pregnancy Research Ethics for Vaccines, Epidemics, and New Technologies (PREVENT) project—explain the challenges pregnant women face in getting vaccinated and what the future may hold.

How will we know if a coronavirus vaccine is safe for pregnant women?

The first step is really to see how people respond to the vaccines currently being tested, with a particular focus on healthy women who are of childbearing age but are not pregnant. What is learned about the safety and side effects of these vaccines will help experts in maternal fetal medicine, ethics, and other fields make recommendations about which vaccines should be evaluated in pregnant women.

Why aren't pregnant women in trials right now?

There are good reasons not to start out with pregnant women as the first group to enroll in clinical trials. Many of the vaccines under development are still in the earlier stages of clinical trials, which focus on whether the vaccine is safe and if it might lead to an immune response. Researchers considering whether to enroll pregnant women in later-stage vaccine trials should consider the potential risks and benefits based on available evidence from these earlier trials.

As more and more vaccine candidates progress to later-stage trials, we want to make sure that pregnant women have fair opportunities to participate in studies that may benefit them and their babies. We also want to make sure that their interests are taken into account from the outset so that we can generate the best possible evidence about safe and appropriate use of vaccines in pregnancy.

That means leveraging every opportunity to collect relevant information. For example, even when a vaccine trial is not deliberately enrolling pregnant women, some women may become pregnant during the trial. (This is especially likely in the Warp Speed trials—each of which will enroll about 30,000 people). So, it’s important for researchers to plan to systematically capture data relating to pregnancy and infant outcomes for women who become pregnant during those trials.

When a vaccine is approved and is being rolled out nationwide, should a pregnant woman get the vaccine?

First, there’s no approved vaccine right now so it’s impossible to say. But we can say that when there is one, there will be a very limited supply initially, and it will be offered to only high-priority groups. It is likely that one of these groups will be frontline workers. Of course, a lot of them are women of childbearing age such as doctors, nurses, food workers, and so on.

When the very first vaccine becomes available, it is unlikely that there will be evidence yet from trials including pregnant women. And even if we have some insights from women who become pregnant in the large efficacy trials, it’s still unlikely that pregnant women will be among the first to get the vaccine.

Another factor to consider: By early 2021, we’ll have more data on the coronavirus’s effects in pregnancy. That evidence is important because it tells us about risk. If the virus presents a major risk to pregnant women, then it's possible that pregnant women might be offered a vaccine sooner. Decisionmakers should always weigh the risk of vaccination compared with the risk of being unvaccinated against a disease that can cause serious harms. By next year, we will hopefully have a clearer picture on both sides of the equation.

What if you’re a frontline worker who is pregnant, should you get vaccinated if you can?

One of the things that we have said in our work is that simply being pregnant shouldn’t automatically exclude a woman in a high-risk group from receiving a vaccine.

The risks and benefits should be weighed. It's like a three-legged stool.

  • What do we know about the vaccine’s safety?
  • What do we know about the risks a pregnant woman faces if she gets infected?
  • How likely is it that she will become infected given her community and her job?

All these things have to be considered. Then we have to think about what’s the most ethical thing to do—even when there are no good options.

Are some vaccines more suitable for pregnancy than others?

There are different types of vaccines that use different approaches to generate immunity against a threat like COVID-19. Some have been commonly used in vaccines that we offer to pregnant women against other types of diseases; we have more experience with those types of vaccines. Ultimately, we will need to understand more about the immune response and the safety profiles of these various types of vaccines to make recommendations about evaluation and use.

If we see safety signals that suggest that a particular vaccine or vaccines may not be ideal for pregnant women, it will become really important that other candidates in the COVID-19 vaccine pipeline are prioritized.

The important thing is that pregnant women should not be left behind as these new technologies and new vaccines are developed. Their needs should be considered.

Ruth Faden, PhD, MPH, is the founder of the Johns Hopkins Berman Institute of Bioethics and its director from 1995 until 2016; Ruth Karron, MD, is the director of the Center for Immunization Research and the Johns Hopkins Vaccine Initiative at the Johns Hopkins Bloomberg School of Public Health; and Carleigh Krubiner, PhD ’15, is a policy fellow at the Center for Global Development. They are co-authors of “Pregnant women & vaccines against emerging epidemic threats: Ethics guidance for preparedness, research, and response,” which was published in Vaccine in 2019.