Skip to Content

NorthShore’s online source for timely health and wellness news, inspiring patient stories and tips to lead a healthy life.

Healthy You

COVID Fact: Science & Data Show Vaccines Do NOT Affect Fertility

Thursday, May 13, 2021 8:19 AM

The excitement is palpable among parents anxious to get their kids vaccinated against COVID-19, now that the FDA has authorized the Pfizer vaccine for children, ages 12 to 15. NorthShore has started offering vaccines to this age group.


Jennifer Grant, MD, NorthShore University HealthSystem Infectious Disease expert, wants to remind parents that the mRNA vaccines are safe and effective for children. Here, Dr. Grant sets the record straight about false reports claiming the mRNA vaccines affect fertility and answers questions about COVID vaccines:

Do the COVID-19 mRNA vaccines make people infertile? 
No. Early on after the vaccines were approved, we started seeing misinformation on the Internet that the protein the mRNA recipe makes – the spike protein – is very similar to a protein that is involved in the placenta of a pregnant woman called syncytin-1.

This then led to concerns that the vaccine would cause a woman’s body to make antibodies that will attack that protein in the placenta, causing infertility or pregnancy loss. In reality, the proteins are quite different. Structurally, the shape of the spike protein and the syncytin-1 protein are not similar, and the antibodies made by the human body do not attack the placenta. So the science behind this, even theoretically, is not valid.

And even better is that we continue to get more and more real-world data about vaccines in pregnant women. Initially, we had a very small amount of initial data from both the Pfizer and Moderna trials. Combining both of those trials, about 36 percent of women did get pregnant or find out they were pregnant after receiving a vaccine. Half were in the placebo group and half were in the vaccine group. There were no pregnancy adverse effects that happened in women who had received the vaccination and got pregnant.

Last month, a much larger study was published in The New England Journal of Medicine that reviewed over 35,000 women in the v-safe registry who identified as pregnant and received the vaccine, and found no sign that the vaccine caused harm to the pregnant women or fetus. On the contrary, we know that COVID-19 can make pregnant women quite sick; the risk of that far outweighs any risk from the vaccine.

“I am very excited for my son and daughter to eventually get the vaccine and fully encourage parents to vaccinate their children.”
--Jennifer Grant, MD, NorthShore University HealthSystem Infectious Disease expert

Does it affect male fertility?
No. There is no data that it affects male fertility.

How does vaccine misinformation spread?
I think this myth had just enough science to sound plausible and then capitalized on the fear and uncertainty that we have all been living with throughout this pandemic. So this fertility story was a perfect set-up to spread like wildfire.

Obviously, these are new vaccines using novel technologies and it’s totally understandable that people are going to be skeptical and want to do their own research. But we always have to come back to the science and the data and remember to make sure that any online research we are doing comes from reputable sources.

As a young woman, I had no qualms about getting vaccinated, in fact, I was thrilled. I fully recommended and supported my younger sister and my friends to do the same. I am very excited for my son and daughter to eventually get the vaccine and fully encourage parents to vaccinate their children.

I have seen the devastation that COVID-19 has brought to families for the past year. I know the risks of COVID-19, and they far, far outweigh the risks of the vaccine.