Abstract

Despite the demonstrated safety of COVID-19 mRNA vaccines, a previous survey demonstrated that unknown long-term affects to fertility was a major reason for vaccine hesitancy. We conducted a single-center prospective study to investigate the long-term impact of COVID-19 vaccination on sperm parameters of healthy men. We hypothesized that COVID-19 vaccination (and booster doses) would not negatively impact sperm parameters in the long-term. Twelve healthy male volunteers between the ages of 18-50 years old with pre-vaccination semen analyses completed follow-up analyses between September 2021 - March 2022. Participants were required to provide documentation demonstrating at least two mRNA vaccine doses. Semen analyses evaluated volume, sperm concentration, total motility, and TMSC. The number of days abstinent prior to sample collection was documented during the visit. The primary outcome was median change in the total motile sperm count at least 9 months following fully vaccinated COVID-19 status. Individuals who admitted a history of infertility or previous azoospermia were excluded from study participation. After calculating data distribution on normality test, medians, and interquartile ranges (IQRs) were reported for all variables. The Wilcoxon rank sum test was used to compare pre- and post-vaccination semen parameters. A 2-tailed P < .05 was considered statistically significant. A total of 12 men volunteered in our study median age 26 [25 - 30] years. Subjects provided follow-up semen samples at a median of 10.5 months following the second vaccine dose. There were no significant changes in any semen parameters at baseline, 3 months, or 10 months following vaccination. Baseline samples demonstrated median sperm concentrations and TMSC of 29.5 million/cc [9.3 – 49] and 31 million [4-51.3], respectively. At follow-up, sperm concentration and TMSC were 43 [20.5 – 63.5] (p=0.407) and 43.5 [8.5 – 102.8] (p=0.519), respectively. Of note, there were no significant changes in semen volume nor total motility (%) at follow-up. Two of the men were oligospermic at baseline. Of these two men, one was found to be normospermic at follow-up and the other remained oligospermic. COVID-19 mRNA vaccines and boosters do not appear to negatively impact the semen parameters of healthy males even 10 months following vaccination. Our study and future studies should add to the growing body of the evidence on the long-term safety of vaccines and potentially decrease vaccine hesitancy.