A study published in the journal Gamete Biology demonstrates that the mRNA-based coronavirus disease 2019 (COVID-19) vaccine developed by Pfizer/BioNTech is not detrimental to sperm health over a long period post-vaccination. 

Study: Sperm quality is not affected by the BNT162b2 mRNA SARS-CoV-2 vaccine: results of a 6–14 months follow-up. ​​​​​​​Image Credit: Yurchanka Siarhei / Shutterstock​​​​​​​Study: Sperm quality is not affected by the BNT162b2 mRNA SARS-CoV-2 vaccine: results of a 6–14 months follow-up. ​​​​​​​Image Credit: Yurchanka Siarhei / Shutterstock


Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative pathogen of COVID-19, enters host cells through the interaction between viral spike protein and host cell receptor angiotensin-converting enzyme 2 (ACE2).

The presence of ACE2 on the blood-testis barrier makes the male reproductive system more susceptible to becoming infected by SARS-CoV-2. In this context, a few studies have shown that SARS-CoV-2 may minorly affect sperm quality within 2 to 3 months post-infection. However, the majority of studies investigating SARS-CoV-2-induced changes in the male reproductive system could not detect viral RNA in the semen.

Studies investigating the impact of COVID-19 vaccination on sperm health have shown that vaccines are safe for use in men. However, most of these studies have examined only the short-term effects of COVID-19 vaccination. The analysis of long-term outcomes is particularly needed to increase vaccine uptake and decrease vaccine hesitancy among men.

In the current study, scientists have evaluated the effect of the mRNA-based COVID-19 vaccine (Pfizer/BioNTech) on sperm quality after six months and 14 months of vaccination.

Study design

The study was conducted on a total of 58 men who were undergoing in vitro fertilization (IVF) treatment and had received two or three doses of the Pfizer/BioNTech COVID-19 vaccine. The study included men with normal and impaired sperm quality before vaccination. In addition, none of the participants had a history of SARS-CoV-2 infection.

Semen samples were collected from the participants before vaccination (baseline) and 6 to 14 months after vaccination. The samples were analyzed for semen volume, total motile count, sperm concentration, motility, and morphology.  

Important observations

Of 58 men included in the final analysis, 16 had abnormal sperm quality, and 42 had normal sperm quality at baseline. The average age of the participants was 38 years. The average duration between vaccination and semen analysis was 317 days.

Specifically, semen analyses were conducted 6 – 9 months and 9 – 14 months after vaccination in 13 and 45 participants, respectively. Considering the entire study population, higher and lower post-vaccination total motile counts were observed in 27 and 28 men, respectively.    

The analysis of pre- and post-vaccination semen samples revealed no significant differences in any tested parameters, including semen volume, total motile count, sperm concentration, morphology, and motility.

Both men with two-dose and three-dose vaccination exhibited similar post-vaccination sperm health except for sperm concentration, which showed higher levels in men with three-dose vaccination.

No significant difference in post-vaccination sperm health was observed between men with normal and abnormal pre-vaccination sperm parameters. Moreover, no correlation was observed between time since vaccination and post-vaccination sperm health.

Study significance

The study highlights that the mRNA-based COVID-19 vaccine (Pfizer) is safe for use in men. The vaccine does not seem to impair the male reproductive system over a relatively long period. Moreover, the safety profile does not seem to depend on the number of vaccine doses or pre-vaccination sperm quality.

As mentioned by the scientists, the study includes men with male factor infertility, which may limit the applicability of findings to the general population.   ​​​​​​