Even before the first COVID-19 vaccine was granted emergency use authorization by the Food and Drug Administration, there were rumors on social media about its risks – in particular, some rumors claimed that the vaccine could cause infertility.
Health experts agree that claims about the vaccine and infertility are entirely unsupported by research, but the rumors have still prompted concern among potential vaccine recipients. Some have considered not getting the vaccine because they’re worried the vaccine could reduce fertility or make them unable to get pregnant in the future.
“This is a vaccine that has been proven to be very safe and very effective,” says Dr. Sarah Haessler, chief epidemiologist and infectious disease specialist at Baystate Health.
What are the side effects of the COVID-19 vaccines?
Both vaccines currently authorized for emergency use – made by Pfizer and Moderna – cause common, minor side effects for up to 50% of people within the first few hours or days after vaccination.
Common side effects include pain or swelling on the arm where you got the shot, and fever, chills, tiredness, and headache. Less common side effects include nausea and swollen lymph nodes.
According to Dr. Haessler, people can expect to have at least one of these side effects 1-3 days after getting the vaccine. However, there is no evidence that there is any danger. “These effects are a sign that the body is mounting an immune response to the vaccine as intended”, says Haessler.”
Is the vaccine safe for people who are pregnant or want to get pregnant someday?
While the CDC says that getting vaccinated is a personal choice if you’re pregnant, they recommend getting vaccinated because pregnant people are at increased risk for severe illness from COVID-19. “The risk to pregnant people if they get the disease (COVID) is very real,” says Baystate Health obstetrician Dr. Kathaleen Barker.
Dr. Barker explains that, while there were no COVID vaccine studies done on pregnant people or on fertility, there is also no evidence that the vaccine would be dangerous. “There is no data on administration of the vaccine to pregnant people. However, there is no indication that it is not safe among pregnant people.” To learn more about getting the vaccine if you're pregnant, see the University of Massachusetts Medical School – Baystate shared decision-making guide.
For those who are unsure about getting the vaccine, the CDC recommends vaccination, with counseling from a healthcare provider.
Can the COVID vaccine cause infertility?
Experts agree that the COVID-19 vaccines are unlikely to affect fertility. Still, some people who are considering pregnancy or trying to conceive are worried that the vaccine could impact their fertility or eventual pregnancy. These concerns have been stoked by viral social media posts, since widely debunked by health experts, claiming that the vaccines could block a protein necessary for forming the placenta.
The impact on fertility is not studied yet, says Dr. Barker, but “there is no evidence from other work using mRNA (COVID-19 vaccines are based on messenger RNA and not the live virus) to indicate that there would be any impact on a fetus or any impact on someone’s ability to conceive, or on breastfeeding or pregnancy.”
While there is no research on the effects of the COVID-19 vaccines on fertility, we do know that other types of vaccines do not affect fertility. Pregnant women and women who are trying to get pregnant are regularly and routinely vaccinated against a variety of diseases. Both pregnant women and newborns can be more vulnerable to illness than other people.
To better understand why the COVID vaccine is unlikely to affect fertility, it helps to understand what mRNA is.
What is mRNA, and how does it work?
Most vaccines use a weakened or inactivated virus to trigger an immune response in the body. But messenger RNA vaccines—or messenger ribonucleic acid vaccines—are a new type of vaccine to protect people against infectious diseases. mRNA vaccines teach our cells how to make a protein instead of relying on the weakened virus.
RNA is present in all living cells, and acts as a messenger to carry instructions from DNA (short for deoxyribonucleic acid – DNA contains our unique genetic code).
Dr. Haessler explains that the messenger RNA (mRNA) instructs the ribosome (the part of the cell that builds proteins) on how to make a piece of the spike protein found on the outside of a COVID-19 virus.
“The COVID vaccines use a short piece of genetic material called mRNA, which is a short chain of instructions…The ribosome uses that set of instructions to create proteins, and then the messenger RNA disappears because its work is done…Your body starts making these spike proteins, and those proteins initiate the immune response.”
While the mRNA are instructing the body on how to make the spike protein, “the body isn’t making the virus – its making the protein that’s on the surface of the virus. It fools the body into thinking it is seeing the virus when it isn’t,” says Haessler.
After the body reacts to the protein and begins making antibodies, the body has learned how to protect against future infection.
Because of the way mRNA works (it enters the body, does its work, then disappears), doctors don’t see a way that mRNA vaccination could impact something in the future – like fertility or pregnancy.
Learn more about how mRNA works from the UMass Medical School.
What’s the bottom line?
Experts recommend getting the vaccine, especially if you are in a high risk or vulnerable group. In most cases, the risks of COVID-19 are considered much higher than any potential risks from getting the vaccine. If you have concerns about COVID-19 vaccine safety, talk with your healthcare provider.