A newly published study has recorded a temporary reduction in sperm concentration for males who have taken the Pfizer Covid-19 vaccine – but researchers found that vaccination did not have a long-term impact on male fertility.
According to authors of the study, it is the first of its kind to longitudinally assess semen parameters post-vaccination beyond the period of spermatogenesis in men. The researchers were led by Dr. Itai Gat with the Sperm Bank and Andrology Unit at the Shamir Medical Center and Tel Aviv University’s Sackler Medical School.
The researchers are of the belief that the short-term decline in male fertility is due to the development of febrile systemic immune responses as oppose to the direct effects of the Pfizer vaccine on the testicular cells.
In the article published in Andrology, researchers acknowledged concerns around the potential impact Covid-19 vaccinations could have on male fertility, stating: “The development of covid-19 vaccinations represents a notable scientific achievement. Nevertheless, concerns have been raised regarding their possible detrimental impact on male fertility”.
The Israeli study was performed to investigate the impact of the Covid-19 Pfizer vaccine on semen parameters among 37 semen donors from the sperm banks (SB) of Shamir, Sheba, and Herzlyia Medical Centers, Israel.
A total of 220 samples were provided from the three sperm banks. The samples were then included in a retrospective longitudinal multicenter cohort study.
Those who were vaccinated were classified as having received two doses of the Pfizer vaccine, with vaccination completion scheduled seven days after the second dose.
Researchers explained that the study was divided into four phases: baseline or pre-vaccination phase (T0) encompassing one to two semen samples per donor, short-term evaluation phase (T1), intermediate-term evaluation phase (T2), and long-term evaluation phase (T3).
The primary endpoints were semen parameters. Three statistical analyses were then conducted: firstly, a generalised estimated equation model; secondly, first sample, and thirdly, samples’ mean of each donor per period were compared to T0.
The T1, T2, and T3 phases included one to three samples per sperm donor and were obtained 15 to 45 days, 75 to 120 days, and after >150 days of completion of vaccination, respectively. The changes in sperm concentration, semen volume, semen mobility, and total mobility count among donors after they were fully vaccinated was then observed.
Revealing the results, researchers said compared to the T0 phase, they observed a reduction in sperm concentration by 15.4%, with a 22% reduction in the total motile count during the T2 phase. Similarly, analysis of the first sample alone showed sperm concentrations was reduced by 12 x 106/ml; total mobility count was lowered by 31 x 106spermatozoa during the T2 phase in comparison to the T0 phase.
Observing the average sperm parameter values, the corresponding reductions were 9.5 x106/ml and 27 x 106 spermatozoa, respectively; however, researchers noted that the counts recovered during the T3 phase, indicating the detrimental effects of the Pfizer vaccination on male fertility were short-term. They also noted that vaccination had no significant impact on semen volume of sperm mobility.
Researchers wrote: “This longitudinal study focused on SD demonstrates selective temporary sperm concentration and TMC deterioration three months after vaccination followed by later recovery verified by diverse statistical analyses”.
In conclusion, they said: “Systemic immune response after BNT162b2 vaccine is a reasonable cause for transient semen concentration and TMC decline. Long-term prognosis remains good”.