No, the coronavirus vaccine won't make you infertile

• A now-blocked Facebook post that went viral claimed the coronavirus vaccine could cause infertility.
• It suggested incorrectly that the vaccine teaches the body to attack a protein involved in placental development.
• In reality, the protein the vaccine spurs the body to make and attack bears little resemblance to the one in the placenta.
• Although data is still lacking as to how the coronavirus vaccine works in pregnant women, experts expect it to be safe and say that women who are pregnant or of childbearing age should be able to get it if they want.

A post that was circulating on social media falsely claimed that Pfizer's new coronavirus vaccine could cause infertility in women. The vaccine is "female sterilization," an image in the post said, incorrectly attributing the myth to the "head of Pfizer research."

The post, which has since been blocked by Facebook as "false information," promoted an incorrect idea that the vaccine spurs the immune system to attack both a protein in the coronavirus and also a protein involved in the formation of the placenta - the organ that delivers oxygen and nutrients to the fetus during pregnancy.

But experts say there's no evidence the vaccine could lead to infertility.

"Based on the way it's made, it should be safe," Dr. Zaher Merhi, an OB-GYN, reproductive endocrinology and infertility specialist, and the founder of Rejuvenating Fertility Center, told Insider.

The protein the vaccine teaches the body to fend off is not the same as the one involved in placental formation

According to USA Today, the post, written by an unidentifiable author, said: "The vaccine contains a spike protein (see image) called syncytin-1, vital for the formation of the human placenta in women."

"If the vaccine works so that we form an immune response AGAINST the spike protein, we are also training the female body to attack syncytin-1, which could lead to infertility for an unspecified duration."

That's not true. First, the vaccine does not contain syncytin-1, but rather mRNA: genetic instructions that spur the body to produce, and therefore recognize, the unique spike protein that the novel coronavirus uses to latch onto cells.

While it's true that syncytin-1 and the coronavirus's spike protein share a small amino acid sequence, they are not interchangeable.

"It has been incorrectly suggested that COVID-19 vaccines will cause infertility because of a shared amino acid sequence in the spike protein of SARS-CoV-2 and a placental protein," Pfizer spokeswoman Jerica Pitts said in an email to the Associated Press. "The sequence, however, is too short to plausibly give rise to autoimmunity."

The theory also suggests that syncytin-1 is the one and only protein important for placental development, but it's more complicated than that. A sibling protein, syncytin-2, for instance, helps prevent the mother's immune system from attacking the fetus.

Plus, the vaccine prompts the body to produce antibodies very similar to the natural ones produced in response to infection. If those antibodies attacked the placenta, we'd to see high rates of placental complications and miscarriages among the more than 44,000 pregnant women who've gotten the coronavirus, Dr. Mary Jane Minkin, clinical professor of obstetrics and gynecology at Yale School of Medicine, told USA TODAY.

What's more, some people have gotten pregnant while participating in clinical trials and receiving a vaccine. These women are still being tracked, but if the vaccine prevented pregnancy, their pregnancies wouldn't have been possible.

Pregnant women and those who may become pregnant can get the vaccine if they want to

Pregnant women were excluded from clinical trials, so we don't know the real-world effects of the vaccine in that population. But experts say it should be safe, since the vaccine, like the flu vaccine, does not contain live virus.

The mRNA is "not going to be able to enter the cell of the baby and cause any problem, mechanistically speaking," Merhi told Business Insider.

As the American College of Obstetricians and Gynecologies (ACOG) says in its advisory about vaccination in pregnant and lactating people, "these vaccines do not enter the nucleus and do not alter human DNA in vaccine recipients. As a result, mRNA vaccines cannot cause any genetic changes."

The organization, along with the Centers for Disease Control and Prevention and the Food and Drug Administration, says pregnant women who want the vaccine should be able to get it.

People who are in prioritized vaccination groups and are actively trying to become pregnant or are contemplating pregnancy should also get vaccinated, ACOG says. There's no need to delay pregnancy after getting the vaccine, according to the group.

Getting COVID-19 while pregnant puts people at a higher risk of being admitted to the intensive-care unit, needing ventilators or life support, and dying than patients who aren't pregnant, according to a November CDC report. So Dr. Rahul Gupta, chief medical and health officer at March of Dimes, previously told Insider anyone who could get pregnant should be a top priority for vaccination.

"We've got to make sure we make an active effort ... to ensure that childbearing-age women, especially minorities, are able to get the vaccine even before they get pregnant," he said.

• Read more:
• Pregnant women aren't prioritized for coronavirus vaccinations, despite being a high-risk group for complications
• What you can and can't do after getting the coronavirus vaccine
• What pregnant women should know about the coronavirus
• What it's like to go through menopause at age 24, with night sweats, weight gain, and infertility