A study conducted on a small group of healthy men shows that no significant decrease in sperm parameters was observed after the administration of two doses of a messenger RNA vaccine against Covid-19.
- Conducted among 45 healthy adult men who received two doses of mRNA vaccine (Pfizer or Moderna), the study shows that vaccination did not affect the quality, concentration or motility of sperm.
- Men with low sperm count even showed a significant increase in motile sperm count after their second dose.
Do messenger RNA vaccines harm male fertility? While in France, nearly 70% of the adult population has now received a complete vaccination schedule, this argument has long been brandished by the “antivax” to justify their refusal of vaccination. According to them, messenger RNA vaccines (Pfizer and Moderna) would be likely to harm fertility and even make you sterile.
A study published last June in JAMA shows that, on the contrary, these vaccines have no effect on sperm parameters, namely their concentration, their mobility or their total number.
More numerous and mobile sperm
This single-center prospective study was conducted by researchers at the University of Miami (USA) with 45 healthy men aged 18 to 50 (median age 28) from December 2020 to January 2021. All provided a semen sample after 2 to 7 days of abstinence, before receiving a first dose of vaccine. 21 (46.7%) received the vaccine from Pfizer and 24 (53.3%) received the vaccine from Moderna. A second semen sample was provided approximately 70 days after the injection of the second dose.
Analyzes performed by the researchers included measurement of semen volume, sperm concentration, sperm motility, and total motile sperm count (TMSC).
The results showed that the median baseline sperm concentration and TMSC were 26 million/mL and 36 million, respectively. After the second dose of vaccine, the median sperm concentration increased significantly to 30 million/mL and the median TMSC to 44 million. But that’s not all, since the results also show a significant increase in semen volume and sperm motility.
Of the 45 participants, 8 were oligospermic before the vaccine, that is, they had an abnormally low concentration of sperm in their semen. Of these 8 volunteers, 7 increased their sperm concentration.
Limits under study
For the researchers, these results show that vaccines containing mRNA and not the live virus do not affect the quality or quantity of sperm. However, they warn that these results should be put into perspective, as they were obtained on a limited sample of participants, in good health, and in the absence of a control group. In addition, they recognize that this increase in sperm parameters may also be due to the lengthening of the abstinence period before the second sample.
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