Does mRNA SARS-CoV-2 vaccine detrimentally affect male fertility, as reflected by semen analysis?

Research question: Does Pfizer's coronavirus disease 2019 (COVID-19) vaccination detrimentally affect semen analysis parameters? Design: A prospective cohort study was conducted at a single large tertiary centre in Israel between February and March of 2021. Semen samples from 75 fertile men were analysed 1–2 months following their second dose of Pfizer's COVID-19 vaccine. The semen parameters were compared with the World Health Organization (WHO) reference ranges. The primary outcome was the percentage of abnormal semen parameters in those who were vaccinated, i.e. the rates of oligozoospermia, reduced percentage of motile spermatozoa and abnormal sperm morphology. Results: The interval from the time of the second vaccination to the date of participation was on average 37 days, with most subjects describing either mild or no side effects after the first or second dose. The mean sperm concentration was 63.2 ± 33.6 × 10⁶/ml, with only a single participant (1.3%) with a sperm count of 12.5 × 10⁶/ml, considered by the WHO to be oligozoospermic. The mean sperm motility percentage was 64.5 ± 16.7%, with only a single man (1.3%) displaying reduced motility. No notable morphological abnormalities were observed. This constituted a lower percentage of abnormal semen parameters compared with the 5% rates reported in fertile men by the WHO. Conclusions: The semen parameters following COVID-19 vaccination were predominantly within the normal reference ranges as set by the WHO and do not reflect any causative detrimental effect from COVID-19 vaccination. The results strengthen the notion that the Pfizer's severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine is safe and should be recommended to men wishing to conceive.