Vaccines cause infertility
No scientific evidence links any vaccine, including COVID-19 vaccines, to infertility in men or women. Multiple large prospective studies, systematic reviews, and major reproductive medicine organizations have investigated this specific claim directly and found no supporting evidence.
What we know
The claim that vaccines cause infertility gained significant traction during the COVID-19 pandemic, spreading rapidly through social media in 2020 and 2021. Its most widely circulated form relied on a specific molecular argument: that the spike protein used by mRNA COVID-19 vaccines to train the immune system shares structural similarity with syncytin-1, a protein involved in placental formation, and that antibodies generated against the spike protein might therefore cross-react with and impair syncytin-1, disrupting fertility or pregnancy. This mechanistic argument was scientifically implausible from the outset, since the structural similarity between the two proteins is extremely limited, but it circulated widely enough that it required direct empirical investigation rather than dismissal on theoretical grounds alone.
That investigation has now been carried out at considerable scale. A large prospective cohort study following couples trying to conceive found no difference in fecundability, the probability of conception in a given menstrual cycle, between vaccinated and unvaccinated women, and also found no effect from male partner vaccination on couples' ability to conceive. A separate study specifically examining in vitro fertilization outcomes found no significant differences in egg retrieval numbers, fertilization rates, or embryo quality between vaccinated and unvaccinated women undergoing IVF treatment, providing granular, mechanism-level reassurance beyond simple pregnancy rate comparisons.
Male fertility has received similarly direct scrutiny. Multiple studies measuring sperm parameters, including sperm count, concentration, motility, and morphology, before and after COVID-19 vaccination found no clinically significant negative changes attributable to the vaccine. Some of these studies specifically noted that COVID-19 infection itself, as opposed to vaccination against it, has been associated with temporary reductions in sperm quality in some men, an important asymmetry that runs opposite to the direction the infertility myth assumes, since it means avoiding vaccination while remaining susceptible to infection may carry more reproductive risk, not less.
The American College of Obstetricians and Gynecologists (ACOG), the American Society for Reproductive Medicine (ASRM), and the World Health Organization have all reviewed this body of evidence and issued statements affirming that there is no scientific evidence connecting COVID-19 vaccines, or any other recommended vaccine, to infertility in men or women. These organizations have specifically recommended vaccination for women who are pregnant, breastfeeding, or planning pregnancy, based on the combination of no demonstrated fertility risk and well-documented risks of severe COVID-19 illness during pregnancy, including elevated risk of preterm birth and ICU admission for the pregnant person.
The infertility myth did not originate in a scientific vacuum; it drew on a longer history of vaccine hesitancy narratives that have previously targeted other vaccines with similar reproductive-harm claims, including unfounded assertions made in past years about tetanus vaccination campaigns in some countries being secretly designed to reduce fertility. Public health researchers studying misinformation note that reproductive-harm claims are a recurring and effective category of vaccine myth because they tap into protective instincts around fertility and family formation, and because the biological processes involved, endocrinology and reproduction, are complex enough that a plausible-sounding mechanistic story can gain traction before the relevant empirical research catches up and definitively closes the question, as it has here.
Common claims
- COVID-19 vaccines cause infertility in women.Not supported
- Vaccine spike protein antibodies attack placental proteins.Not supported
- COVID-19 vaccination affects male sperm quality.Not supported
- COVID-19 infection itself can temporarily affect sperm quality.Partly supported
Evidence hierarchy
All sources
- COVID-19 vaccines and fertility statementAmerican College of Obstetricians and Gynecologists (ACOG) · 2023
- COVID-19 vaccines, pregnancy and fertilityWorld Health Organization · 2023
- Effect of COVID-19 vaccination on fertility and IVF outcomesAmerican Journal of Obstetrics and Gynecology · 2022
- Sperm parameters following COVID-19 vaccinationJAMA · 2021