New research has looked into the claim COVID-19 vaccines affect fertility, something often cited as a reason for vaccine hesitancy. It found the vaccine doesn't affect fertility but getting COVID might.

The study, led by Boston University School of Public Health (BUSPH)and published in the American Journal of Epidemiology, found no link between COVID-19 vaccination and fecundability, the probability of conception per menstrual cycle. The analysis did find a link between male fertility and getting the COVID-19, albeit temporarily. Vaccination prevents this.

“Many reproductive-aged individuals have cited concerns about fertility as a reason for remaining unvaccinated,” lead author Dr Amelia Wesselink said in a statement. “Our study shows for the first time that COVID-19 vaccination in either partner is unrelated to fertility among couples trying to conceive through intercourse. Time-to-pregnancy was very similar regardless of vaccination status.”

The analysis was conducted on survey data on fecundability and COVID-19 vaccination and infection. The survey in question was the BUSPH-based Pregnancy Study Online (PRESTO). The participants included 2,126 women in Canada and the US who provided information on sociodemographics, lifestyle, medical factors, and characteristics of their partners. The data was collected from December 2020 to September 2021, and the participants were followed in the study through November 2021.

Fecundability in female participants that had at least one dose of the vaccine was no different for unvaccinated female participants. The same was found with male partners who were vaccinated and unvaccinated. The study went further by looking at the number of vaccine doses participants had had, the brand of vaccine (Pfizer-BioNTech, Moderna, or Johnson & Johnson), history of infertility, where they are from, and what they do in life. Being vaccinated for COVID-19 appeared to have no effect on fertility.

However, while the vaccines do not play a role, the virus unfortunately does. The team found that men who tested positive for COVID in the last two months of a given menstrual cycle had lower fertility than men who had never tested positive or men that had tested positive more than 60 days ago. This finding is in agreement with other studies on how the virus can affect the penis and testicles.

“These data provide reassuring evidence that COVID vaccination in either partner does not affect fertility among couples trying to conceive,” said senior author Dr Lauren Wise, professor of epidemiology at BUSPH. “The prospective study design, large sample size, and geographically heterogeneous study population are study strengths, as was our control for many variables such as age, socioeconomic status, preexisting health conditions, occupation, and stress levels.”