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 and rejected this claim.
What we know
Misinformation linking vaccines to infertility has circulated for decades. In the COVID-19 pandemic context, a specific claim arose that the mRNA spike protein resembled syncytin-1, a protein involved in placental development, and that vaccine-induced antibodies would cause anti-placental autoimmunity and female infertility. Scientists rapidly identified that the sequence similarity between the spike protein and syncytin-1 is limited to only four or five amino acids, far too brief a sequence to trigger meaningful cross-reactivity.
A prospective cohort study funded by the National Institutes of Health followed more than 2,000 couples trying to conceive and found no difference in pregnancy rates between couples where one or both partners had received COVID-19 vaccines and unvaccinated couples. A systematic review published in the European Journal of Public Health analyzed studies on COVID-19 vaccines and fertility parameters in men, including sperm motility and concentration, and found no significant differences between vaccinated and unvaccinated individuals.
Organizations including the CDC, WHO, ACOG, ASRM, and SMFM have all issued statements confirming that there is no credible mechanism by which COVID-19 vaccines or other vaccines cause infertility. Temporary minor changes in menstrual cycle timing have been reported following some COVID-19 vaccines, but these are distinct from fertility and do not persist.
In contrast, COVID-19 infection itself has been associated with temporary reduction in sperm quality in infected men for up to 60 days, suggesting that vaccination is protective for male fertility outcomes relative to infection.
Common claims
- COVID-19 vaccines cause female infertility via syncytin-1No scientific basis
- Vaccines alter sperm qualityNot supported by evidence
- Vaccines change menstrual cycles permanentlyTemporary changes reported, not fertility effects
- Many pregnancies occurred after COVID vaccinationTrue - confirms lack of infertility effect
Evidence hierarchy
All sources
- COVID-19 Vaccination for People Who Would Like to Have a BabyCDC · 2024
- The impact of Covid-19 vaccines on fertility: a systematic reviewEuropean Journal of Public Health · 2022
- Sources of Vaccine Hesitancy: Pregnancy, Infertility, Minority IssuesOpen Forum Infectious Diseases (PMC) · 2021
- COVID-19 vaccine: can it affect fertility?Irish Journal of Medical Science (PMC) · 2021
- Prospective Cohort Study of COVID-19 Vaccination and FertilityAmerican Journal of Epidemiology · 2022