The effect of mRNA technology vaccines on fertility is something that "brakes" many. Eventually, mRNA vaccines affect the sperm;
Because coronavirus SARS-CoV-2 infection has been associated with a reduction in sperm quality and quantity parameters, a relatively small study from the US investigated changes in these parameters before and after administration of an mRNA vaccine.
The Professors of the Therapeutic Clinic of the Medical School of the National and Kapodistrian University of Athens, Efstathios Kastritis and Thanos Dimopoulos (Rector of EKPA), summarize the data of this study.
What a new study showed
In this prospective study done at the University of Miami (published in the medical journal JAMA) healthy volunteers aged from 18 to 50 years, who had planned to be vaccinated with mRNA vaccine.
Participants were tested, to ensure that they did not have underlying fertility problems and those with COVID-19 symptoms or a positive test within 90 days were excluded from the study. Participants provided a sperm sample after 2 to 7 days of abstinence, before receiving the first dose of the vaccine and approximately 70 days after the second dose.
Between 17 December 2020 and 12 January 2021, 45 volunteers (middle-aged 28 years) joined the research. Samples for sperm reassessment were taken at mid-term 75 ημερών μετά τη δεύτερη δόση του εμβολίου.
The study ended on 24 April 2021. The original samples (before the vaccine) taken after an average abstinence period 2.8 days and follow-up samples (after the 2nd dose) μετά από διάμεση αποχή 3 days. From the 45 men, the 21 (46,7%) received BNT162b2 (the Pfizer vaccine) and the 24 (53,3%) received mRNA-1273 (of Moderna).
The median number of sperm per ml of sperm before 1the dose was 26 millions / mL and the median number of motile sperm 36 millions.
What happens in the second dose
After the second dose of the vaccine, the median number of sperm per ml of sperm increased to 30 millions / mL (P = 0,02) and the median number of total motile sperm in 44 millions (P = 0,001). Sperm volume and motility also increased.
Eight of them 45 men were oligospermic before the vaccine (median concentration, 8,5 millions / mL. From them, the 7 άνδρες είχαν αυξημένη συγκέντρωση σπέρματος σε φυσιολογικό εύρος μετά τη 2the dose (median sperm count 22 millions / mL) and 1 person remained oligospermic. None of the participants became azoospermic after the vaccine.
In essence, this study concludes that mRNA technology vaccines against COVID-19 do not affect any sperm health parameters.. also, because vaccines contain mRNA and not live virus, it is unlikely that the vaccine will affect sperm parameters.
Although the results showed statistically significant increases in all sperm parameters, the magnitude of this change is within the normal range. However, men with oligospermia showed no further reduction.
The main limitations of the study include the small number of men who joined the study, who were young and healthy men and relatively short follow-up (However, The study time frame includes the complete life cycle of the sperm, which is about 70-75 days).
And other interesting facts
The data from this study should, also, to be compared with other studies, who have examined the effect of COVID-19 infection on sperm production and quality. The ACE2 receptor, through which the SARS-CoV-2 virus enters the cells, using the spike protein, is abundant in the testicles, where spermatogenesis takes place.
Typically it is stated that the parameters of sperm quality seem to be adversely affected among male patients with confirmed COVID-19, compared to healthy controls, at least in the short term and are associated with significant disturbances in sperm volume, in concentration, in the number, in sperm motility and morphology, of sperm and the number of sperm.
On the possible long-term effects of COVID-19 infection on fertility, new scientific studies are imminent.