No effect on sperm 9 months after COVID-19 mRNA vaccination

The coronavirus disease 2019 (COVID-19) vaccine is effective in reducing deaths from infection with the causative severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Moreover, widespread vaccination against COVID-19 has been successful in reducing infection rates and severe COVID-19 outcomes.

SARS-CoV-2 infection has previously been reported to adversely affect male fertility, as indicated by a transient decrease in sperm production. Current COVID-19 messenger ribonucleic acid (mRNA) vaccine has little or no effect on male fertility, but concerns about potential reproductive toxicity remain a major deterrent to vaccines.

study: Long-term evaluation of sperm parameters after COVID-19 mRNA vaccination. Image Credit: Phonlamai Photography/

Recent F&S report A study in the journal compared the effects of the COVID-19 vaccine on male fertility at a median of 9 months after receiving two doses of the mRNA vaccine.

About research

The current study was conducted at the University of Miami between September 2021 and March 2022. A total of 45 male participants ranging from age 18 to age 50 who had previously participated in another study by the current author were contacted for the current study.

Volunteers with a history of at least two mRNA vaccinations in the last 9 months were included in the study. Participants who had a history of COVID-19 in the past 3 months were excluded from the study.

Participants with a history of decreased sperm parameters, a history of azoospermia, or receiving anabolic steroids or testosterone replacement therapy within the past year were also excluded.

Altogether, 12 were available for follow-up studies. All study participants maintained her abstinence for 2–5 days prior to semen sampling.

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Each semen sample was analyzed for its volume, total motility, and total motile sperm count (TMSC). Median changes in TMSC values ​​were compared at baseline, 3 months, and at least 9 months after vaccination.

Survey results

Samples were collected at a median of 11 and 10 months after receiving the first and second doses of COVID-19 vaccine, respectively. Six participants had received a booster dose a median of 2 months prior to sample collection.

Seven of the study participants received a primary vaccine series containing the Moderna mRNA1273 vaccine, while the remaining five participants received the Pfizer Biontech BNT162b2 vaccine.

Median TMSC values ​​were 31 million, 33 million, and 37.5 million at baseline, 3 months, and at least 9 months after COVID-19 vaccination. Taken together, TMSCs were not significantly different at any time point in the current study.

Semen samples from three participants showed oligospermia at baseline, two of which became normal specie at 3 and 9 months post-vaccination. The remaining semen samples continued to show oligospermia at all time points.


No significant changes in semen parameters were observed 3 months after COVID-19 vaccination compared to baseline values. This finding was consistent with previous reports.

Preservation of sperm characteristics after vaccination may be attributed to the mechanism of action of mRNA vaccines, the lack of live virus and the inability of these vaccines to alter human genetic material.

Furthermore, due to the presence of the blood-testis barrier, the mRNA within the COVID-19 vaccine did not localize to the gonad. With evidence showing that mRNA vaccines do not affect ovarian reserve in women, the results of the current study should reassure vaccine-hesitant individuals who are concerned about their reproductive health and fertility. I can.

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Nonetheless, further research is needed to determine the long-term effects of the COVID-19 vaccine on human sperm quality and viable pregnancy rates.

Journal reference:

  • Diaz, P., Dullea, A., Patel, M., and others. (2022). Long-term evaluation of sperm parameters after COVID-19 mRNA vaccination. F&S reportdoi:10.1016/j.xfre.2022.07.007.

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