On November 5, Green Bay Packers quarterback Aaron Rodgers became the latest celebrity to express concern about COVID-19 vaccination and infertility, when he told the Pat McAfee Show that he avoided the vaccine because of worries over sterility. “The next great chapter of my life, I believe, is being a father and it’s something that I care about a lot,” Rodgers said.

Rodgers isn’t alone in his worries, but that doesn’t mean he’s right. The fertility myth has been one of the most persistent misconceptions dogging this almost year-long vaccination campaign. Now, just days after Pfizer’s vaccine was recommended by the CDC for elementary-aged children, experts are concerned that the myth will prevent parents from taking this crucial step in ending the pandemic.

Two thirds of parents of 5 to 11 year olds cited concerns about their children’s future fertility as reasons for not vaccinating, in a survey published in the Kaiser Family Foundation’s most recent COVID-19 Vaccine Monitor. In addition, studies since the vaccines were first granted Emergency Use Authorization last December have shown that this myth has been a key motivator for people to not get vaccinated.

“There’s absolutely no evidence that the vaccines cause infertility,” says Sonja Rasmussen, a University of Florida pediatrician and epidemiologist who studies COVID-19 vaccination and pregnancy. Thousands of people have gotten pregnant since being vaccinated, she says. In addition, numerous studies of vaccinated people have demonstrated that COVID-19 vaccination has no impact on either female or male fertility. Multiple studies have shown that the vaccine is safe and effective in pregnant people.

Rasmussen had no hesitation in recommending the vaccine to her own 28-year-old daughter and 25-year-old son. “The data we have right now has shown that young people can receive this vaccine, that it’s safe, and that it is effective,” she says. “There’s no way, if I had concerns about fertility or any long term effects, that I’d have pushed my kids to get the vaccine the minute they were eligible.”

Still, doctors around the country are encountering this myth among their patients. Laura Morris, a family physician who practices in Missouri, has heard about it so many times that she now proactively brings it up when unvaccinated patients or their unvaccinated family members come in.

“There’s a group of patients and parents that really want to hear from their doctor,” she says. Once they’ve heard from her that there’s no reality to this myth, they’re reassured. Others have questions about the science behind the vaccine, and she spends time explaining it to them.

As vaccine eligibility has been expanded to ever-younger patients, Morris finds herself having to address concerns about vaccination for people at different stages of life. Earlier in the pandemic most of her questions came from women, but she’s now talking to parents of young boys and girls who are already thinking about grandchildren.

As with every successful piece of false information, the untrue link between vaccination and infertility began with uncertainty. None of the COVID-19 vaccines currently authorized in the United States were trialed on pregnant people at the same time as the general population. That’s normal: pregnant people are “drug orphans,” a term of art for populations who are rarely part of drug trials. But in this case, it did mean that at the end of 2020 doctors and the public found themselves trying to weigh the certain risk of getting COVID-19, which is more severe for pregnant people, against the possible risk of a vaccine.

Expert opinion overwhelmingly suggested that vaccination was the right choice, and the case built as thousands of pregnant healthcare workers opted to be vaccinated. But it wasn’t until April 2021 that the FDA formally recommended the vaccine for pregnant people after a study demonstrated its safety in that population.

In the intervening months, a rumor began by an ex-Pfizer VP turned anti-vaxxer helped to stoke a wildfire. Michael Yeadon, who was the vice president of the German company’s allergy and respiratory research division until 2011, claimed that a tiny similarity between the SARS-CoV-2 spike protein that the vaccines target and a protein found in the human placenta could result in vaccinated people having miscarriages when their body attacked the placenta. This would “result in vaccinated women essentially becoming infertile,” he and a colleague wrote in a December 1, 2020 letter to the European Medicines Agency that asked it to stop trialing the vaccines.

His claims have been debunked. “There is a little tiny area that’s similar,” Rasmussen says, “but certainly not any amount that would make you think it would have any effect on fertility.”

An additional piece of uncertainty was caused by the fact that neither Pfizer nor Moderna’s original trials evaluated reproductive toxicity, says Ranjith Ramasamy, a University of Miami reproductive urologist who has studied the links between COVID-19 and infertility. Again, that’s not unusual: These studies are normally not conducted until Phase 3 of clinical trials, and even then only if it’s expected that pregnant women will be taking the vaccine.

But there was never any scientific reason to suspect that these vaccines could cause infertility. Now we know for sure that they don’t. The study that prompted the CDC to make its recommendation for pregnant women is just one of many going on around the world, none of which have shown there to be any link between COVID-19 vaccination and pregnancy loss or infertility. Studies of men after vaccination, including one authored by Ramasamy, have found the same.

Still, the myth persisted and spread. Google searches for terms like “COVID vaccine fertility” spiked by as much as 700% in the month and a half following the CDC’s emergency authorization for the Pfizer-BioNTech vaccine in December 2020, Ramasamy’s research found.

The irony here is that while the vaccines have never been found to impact fertility, COVID-19 infection has been found to significantly impact male fertility, although there are still many unanswered questions. A COVID-19 infection is also much, much more dangerous for pregnant people, and is associated with a host of negative outcomes for both carrier and fetus, including miscarriage and preterm birth.

“Infertility is something people worry about anyways,” says Rachel Saunders, a University of Kentucky OBGYN. It’s very normal to have concerns about fertility, she says, and that may be one of the reasons why this myth has stuck around.

“It’s not wrong to feel scared,” says Eloho Ufomata, a doctor and professor of internal medicine at the University of Pittsburgh School of Medicine. “It’s not wrong to have concerns and worries.” But “we know that hundreds of thousands of people have gotten vaccinated and have had successful pregnancies,” she says.

Ufomata, who is in her third trimester, posted on social media when she got vaccinated at the end of December 2020—and again recently when she received her booster shot—encouraging her followers to get in touch if they have questions.

She has fielded questions about when to get vaccinated, the risk of pregnancy loss, and fertility. “As a Black physician and as a Black woman, I know about the distrust of the medical system that Black women have due to systemic injustices,” she says. “I think it’s really important, especially during pregnancy, to have someone you trust, and to have these conversations with them.”

Ufomata feels it was a mistake to not include pregnant women in trials of the COVID-19 vaccines. “It allowed a lot of conspiracy theories to flourish, because there was no way to answer those questions,” she says. “And physicians and scientists are very hesitant to answer questions anecdotally or without data.”

This myth shows no signs of slowing its spread and remarks by prominent misinformers are certainly not helping. The experts interviewed for this story are concerned, especially for pregnant people or those who might get pregnant and for children and teens.

“We don’t see any correlation between getting the vaccine and having issues with infertility,” Saunders says, “but we do see very negative effects for pregnant people getting COVID-19.”

Ramasamy is also concerned by reports from his patients that other physicians are counseling them or their partner to wait on COVID-19 vaccination until after pregnancy. “There should be no hesitancy on the physician’s part,” he says.