As U.S. healthcare workers race to immunize as many people as they can against COVID-19, facing enormous political and logistical obstacles, misconceptions and false reports about the dangers of the new vaccines are further complicating their efforts.

One of the more persistent rumors is that the COVID-19 vaccines that the U.S. Food and Drug Administration (FDA) has authorized for emergency use, from Pfizer and Moderna, cause infertility. This allegation is leading many women to think twice about getting immunized.

Is there any scientific evidence behind the claim that COVID-19 vaccines cause infertility?

The answer is no, according to Kristina M. Adams Waldorf, MD, professor of obstetrics and gynecology and an expert in pregnancy infections at UW Medicine in Seattle. This falsehood, she says, “is a very clever way to try to dissuade people from becoming vaccinated — part of a coordinated anti-vax misinformation campaign.”

“We see a lot of anti-vax misinformation that looks like it’s coming from a reputable source,” Dr. Adams Waldorf adds, explaining that this particular claim is especially devious — and effective — because it combines COVID vaccination worries with deep-seated fears that many women have about their fertility and future ability to become pregnant.

The COVID-19 Vaccine Does Not Harm the Placenta

Claims that the COVID-19 vaccine causes infertility focus on the placenta, the organ that a pregnant woman develops to bring nutrients and oxygen to the fetus and remove waste. “What they are purporting is that the vaccine will generate antibodies against part of the coronavirus ‘spike’ protein … and that the same antibodies will cross-react with a protein that is made by the placenta called syncytin-1,” says Adams Waldorf.

Experts in the field have closely studied this issue, and see no reason that the vaccine would act in this way. “There is no similarity between the coronavirus ‘spike’ protein and placental syncytin-1,” Adams Waldorf says.

To find out if there is any basis at all to this theory, scientists have investigated whether blood serum from people who have had COVID-19 and made their own antibodies would bind to placental syncytin-1. The antibodies don’t, Adams Waldorf says.

What’s more, says Adams Waldorf, “We don’t have any reports of infertility in people who have already received the Moderna or Pfizer vaccines; in fact, people in these clinical trials were asked not get pregnant and some got pregnant anyway.”

During the Pfizer vaccine trial, 23 women involved in the study became pregnant, and of those, the only one who lost the pregnancy was a participant from the placebo group.

Does the COVID-19 Vaccine Change DNA?

For people who already feel a vague unease about vaccines, the COVID vaccines manufactured by Pfizer and Moderna may seem especially scary because they use a sophisticated genetic technology.

Unlike vaccines for illnesses like the flu, the Pfizer and Moderna vaccines don’t actually contain weakened or inactivated coronavirus, explains Tarun Jain, MD, associate professor of obstetrics and gynecology in the division of reproductive endocrinology and infertility at Northwestern Medicine in Chicago.

“It can be hard to understand how the COVID-19 vaccine works because it requires a deep understanding of cellular biology. In simple terms, all the vaccine is doing is giving some material — what’s called mRNA [messenger RNA] — that allows our own cells to produce some of the protein called the spike protein that’s found on the surface of the COVID-19 virus,” he says.

After making the spike protein, the cell breaks down the mRNA, says Dr. Jain. “It’s not going into the nucleus, which is where the DNA resides,” he says.

“All [the vaccine] is doing is getting our own body to make some of this spike protein, which will then allow our body to develop an immune response,” says Jain. “It’s not altering our genetics or DNA in any way.”

If You’re Considering Getting Pregnant, the Vaccine Offers Important Protection

Recent findings suggest that COVID-19 poses a greater threat to pregnant women than previously suspected. A small study published in the American Journal of Obstetrics & Gynecology on January 27 found that pregnant women with COVID-19 had a 3.5 times higher rate of being hospitalized for their illness and were 13 times more likely to die of COVID-19 than the general population of the same age.

“Our study really indicates that pregnant women are a high-risk group for COVID-19,” says Adams Waldorf, the senior authority on the paper. “We are concerned that COVID-19-associated maternal deaths have been massively undercounted; we should be very careful with this group and not downplay the risks of what COVID-19 can mean during pregnancy,” she says. “In my opinion, the benefits of vaccination far outweigh the risks in pregnancy.”

Discuss Questions or Concerns About the Vaccine With Your Doctor

“I would highly encourage anyone who’s having questions or doubts to please talk to their doctor or a fertility specialist before making an assumption based what they’ve seen on social media,” says Jain.

“There really are great benefits in having a vaccine to prevent COVID-19 infection,” he says, pointing out that widespread immunity will help people who want to have children do so without the fear of the virus.

“We’re so fortunate that we have the ability to get a vaccine for COVID-19 so quickly,” says Jain. “We really all should take advantage of that protection because the consequence otherwise can be quite dire.”