BU study: COVID-19 vaccines do not cause infection

New findings from investigators at the Boston University School of Public Health indicate that vaccination against COVID-19 does not impair fertility, but men who are infected with the coronavirus may experience a short-term reduction in fertility.

COVID-19 vaccination in either partner does not appear to affect fertility, according to new research by investigators from the Boston University School of Public Health (BUSPH).

Posted in the American Journal of Epidemiology, the prospective study of couples trying to conceive found no association between COVID-19 vaccination and fecundability — the likelihood of conception per menstrual cycle — in female or male partners who received vaccines Pfizer-BioNTech, Moderna or Johnson & Johnson.

In contrast, the results indicate that COVID-19 infection in men can temporarily reduce fertility, an outcome that could be prevented by vaccination.

“Many people of childbearing age cited concerns about fertility as a reason for not being vaccinated,” says the study’s lead author, Dr. Amelia Wesselink, assistant research professor of epidemiology at BUSPH. “Our study shows for the first time that vaccination against COVID-19 in either partner is not related to fertility in couples trying to conceive sexually. Time to pregnancy was very similar regardless of vaccination status.

Wesselink and colleagues analyzed survey data on COVID-19 vaccination and infection, and fecundability, among female and male participants in the BUSPH-Based Online Pregnancy Study (PRESTO), an ongoing NIH-funded study that enrolls women trying to conceive and follows them from preconception through six months postpartum. Participants included 2,126 women in the United States and Canada who provided information on sociodemographics, lifestyle, medical factors, and characteristics of their partners from December 2020 to September 2021, and participants were followed in the study until November 2021.

The researchers calculated the probability of conception by menstrual cycle using participants’ self-reported dates of last menstrual period, typical menstrual cycle length, and pregnancy status. Fertility rates among participants who received at least one dose of a vaccine were almost identical to those of unvaccinated participants. Fertility was also similar for male partners who had received at least one dose of a COVID-19 vaccine compared to unvaccinated male participants. Additional analyzes considering number of vaccine doses, brand of vaccine, history of infertility, occupation, and geographic region also indicated no effect of vaccination on fertility.

Although COVID-19 infection was not strongly associated with fertility, men who tested positive for COVID within 60 days of a given cycle had reduced fertility compared to men who did not. never tested positive or to men who tested positive at least 60 days previously. These data support previous research that has linked COVID-19 infection in men with poor semen quality to other reproductive dysfunctions.

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

The new data also helps ease concerns about COVID-19 vaccines and fertility that stem from anecdotal reports of women experiencing menstrual cycle changes after vaccination.

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About Boston University School of Public Health

Founded in 1976, Boston University School of Public Health is one of the top five private schools of public health in the world. It offers master’s and doctoral level training in public health. The six-department faculty conducts policy-changing public health research around the world, with a mission to improve the health of people – especially the disadvantaged, underserved and vulnerable – locally and globally.


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