COVID-19 vaccines do not cause infertility, health experts say

One of the many persistent falsehoods spread on social media about the vaccines for COVID-19 is that they cause infertility.

According to experts from John Hopkins Medicine, the likely origin of the myth is a false report that arose on social media claiming the coronavirus and the vaccines against it contain a spike protein called syncytin-1. This protein is vital in the development and attachment of the placenta during pregnancy, and damage to it can result in miscarriages as well as infertility.

In truth, however, COVID-19’s spike protein and syncytin-1 do not share a similar genetic code, meaning that the vaccines do not include this heightened risk for infertility.

In an article aimed at debunking myths about the COVID-19 vaccines, doctors at Johns Hopkins University noted that “the two spike proteins are completely different and distinct.”

Dr. Lusine Aghajanova, an assistant clinical professor at the division of reproductive endocrinology and infertility at Stanford, told Yahoo News that these false claims about the coronavirus vaccines affecting fertility in both men and women are “concerning” and have no “scientific basis.”

“We are trying to debunk the myths and also give the scientific background for anything we do,” Aghajanova said. “The short answer to the question — Can [COVID-19] vaccines affect my fertility? — the answer is no,” she added.

A pregnant woman receives a shot in the upper arm
A pregnant woman receives a vaccine for COVID-19 at Skippack Pharmacy in Schwenksville, Pa., on Feb. 11. (Hannah Beier/Reuters)

The infertility myth spread on social media, Aghajanova said, was based on a fundamental misconception of how the vaccines work.

“The mechanism of action of those vaccines doesn’t even give us any theoretical possibility for affecting fertility,” Aghajanova said.

Contrary to rumors, the COVID-19 vaccines don’t contain the live virus that causes COVID-19. They also don’t interact with or alter your DNA in any way. The mRNA vaccines such as those created by Pfizer/BionTech and Moderna use messenger ribonucleic acid (mRNA) to stimulate an immune response that can protect against future infection. Once it delivers the instructions to your cells, the mRNA breaks down and disappears from the body.

In addition, all the COVID-19 vaccines have undergone rigorous safety protocols in order to be granted emergency use authorization by the Food and Drug Administration. These, Aghajanova says, are very reassuring and “show that these vaccines are not only effective, but they’re also safe for a wide range of people, age, ethnicity, sex, etc.”

Concerns about possible infertility may also have stemmed from the fact that pregnant women were excluded from initial clinical trials for the vaccines, a protocol that has been in place ever since the early 1960s, when it was discovered that a sedative called thalidomide, which was used to treat morning sickness and was undergoing clinical trials, caused severe birth defects. Since then, researchers have been cautious about including pregnant women in such trials.

Although pregnant women were not included in the COVID-19 vaccine trials, Aghajanova says, there has been no evidence of loss of fertility in the studies conducted on animals, which were a critical part of the COVID-19 vaccine development process.

Animal testing is a standard process and plays an important role in drug and vaccine developement. Regulators require that a manufacturer show a product is safe when used on animals before it can be given to people. Pfizer/BioNTech conducted such studies in animal models to determine whether there were any negative side effects of its COVID-19 vaccine in pregnancy. It concluded there was no evidence of fertility or reproductive toxicity in animals.

Doses of the Pfizer-BioNTech coronavirus vaccine
Doses of the Pfizer-BioNTech coronavirus vaccine are prepped for pregnant women at Skippack Pharmacy in Schwenksville, Pa., on Feb. 11. (Hannah Beier/Reuters)

Moreover, when human trials were approved for COVID-19 vaccines, follow-up data showed that many of the women who participated in them later became pregnant. During the Pfizer/BioNTech vaccine clinical trials, for example, 23 people became pregnant after receiving the vaccine. Aghajanova says that as far as physicians are aware, “there’s no evidence that their fertility has been affected.”

To capture data on the safety of vaccination outside of clinical trials, the Centers for Disease Control and Prevention developed V-safe, a smartphone-based tool that uses text messaging and web surveys to conduct health check-ins on people who have received a COVID-19 vaccine.

The CDC reported on Jan. 27 that about 30,000 pregnant people had already enrolled in the registry. According to an update released by the agency’s COVID-19 vaccine task force in the Advisory Committee on Immunization Practices on March 1, in the enrolled population, there had been 275 completed pregnancies, including 232 live births. The agency said it plans on continuing collecting vaccine safety data on women before, during and after their pregnancies.

Pfizer has also now launched its own clinical trial for its vaccine for women over the age of 18 who are between 24 and 34 weeks pregnant in an effort to assure the public that no causal link with infertility exists.

Another positive sign, Aghajanova says, is that fertility clinics across the nation have not reported a drop in pregnancy rates or an increase in miscarriages since the rollout of COVID-19 vaccines began.

“That’s what concerns people, pregnancy rates and miscarriage rates, and we didn’t see changes. I haven’t seen or heard anything about any clinic in any state raising concern about pregnancy rates dropping after the vaccine started,” she said.

Aghajanova recommends that women who are planning to conceive or are pregnant consider getting vaccinated because of the high risk associated with COVID-19 in pregnancy.

According to the CDC, pregnant women who have COVID-19 are more likely to get severely ill from the disease compared with nonpregnant people. They also appear more likely to develop respiratory complications requiring intensive care and are also more likely to be placed on a ventilator, according to the agency.

Three leading organizations in the country that specialize in pregnancy and fertility — the American Society for Reproductive Medicine, the American College of Obstetrics and Gynecologists and the Society for Maternal Fetal Medicine — all recommend that pregnant women and women of reproductive age get vaccinated.

Finally, Aghanova says, the best advice she can give people who are concerned about the vaccines is to talk to their providers.

“If you have an OB GYN or if you have fertility specialists, I think these people are best equipped to answer your questions,” she said. “If you don’t have those, just talk to your primary care physicians. Don’t try to find answers on Facebook or elsewhere; just talk to people that know the best in this situation.”


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