Scientists perform a meta-analysis of the effects of SARS-CoV-2 on sperm parameters

Infertility is a common disorder of the reproductive system and affects about one-fifth of couples of reproductive age. About 40-50% of all cases are due to male factors.

Global outbreaks of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus have been observed because the male reproductive system may be vulnerable to SARS-CoV-2 infection. It poses a serious risk to reproductive health.

In a new study published in Journal of Assisted Reproduction and Genetics, Scientists conducted a meta-analysis to study the effects of coronavirus disease 2019 (COVID-19) on the male reproductive system.

About research

Many pathological factors, especially viruses, play an important role in causing infertility. First discovered in Wuhan, China in 2019, SARS-CoV-2 demonstrates its ability to cause life-threatening complications in humans. While studying the mode of spread of the virus, scientists have noticed that close contact and droplets are the two main media.

In addition, the presence of SARS-CoV-2 in feces and urine motivated scientists to study the potential adverse effects of the virus on potential sexual transmission and fertility.

Another important observation was high expression levels of angiotensin converting enzyme 2 (ACE2) in the testis. ACE2 is the major receptor molecule for SARS-CoV-2 and binds to host cells to promote entry. This made the male reproductive system more susceptible to SARS-CoV-2 infection. However, the outcome of this link between infections and male fertility is not definitive.

To address the above discussions in the literature, in the current study, researchers conducted a thorough meta-analysis to investigate the potential effects of SARS-CoV-2 on a range of semen parameters. Parameters included sperm volume, motility, sperm count, concentration, and progressive motility. The authors argue that this is the first meta-analysis to dig deeper into the role of this pathogen in affecting male fertility potential.

Survey results

The data collected indicate the potential for SARS-CoV-2 to cause serious damage to the male reproductive system. The virus has been observed to adversely affect many semen parameters. More specifically, researchers have shown that volume, concentration, motility, and sperm count were all reduced in COVID-19 patients, a finding that was consistent across many studies.

A study by German researchers showed no effect of mild COVID-19 infection on testicular and epididymal function, but impaired semen parameters after moderate infection.

However, the small sample size was the main limitation of this study. However, other studies have reported reduced sperm motility and total motile sperm count in patients with a mild history of COVID-19.

Another study conducted by Chinese scientists reported that increased testicular immune response leads to impaired spermatogenesis in SARS-CoV-2 patients. And they also noticed autoimmune epididymitis in some patients. Contradictory results were obtained by Turkish researchers. They did not report any particular adverse effects on male reproductive health in a short period of time.

Studies also show that the adverse effects of SARS-CoV-2 infection on sperm quality may be reversible. Scientists reported that parameters such as sperm count, sperm concentration, and motility were low at the first sampling, but sperm vitality and morphology were unaffected. The former parameter increased after 3 weeks and the amount of morphologically abnormal sperm also decreased during the second sample collection. One potential explanation for this temporary effect could be fever.

There was only one study on the long-term effects of COVID-19 on semen parameters (ie, more than 90 days after recovery). Scientists have stated that the long-term effects may not be due to the direct effects of COVID-19. Psychopathological and stressors can also adversely affect sexual health. There may be other factors that contribute to long-COVID, but they are currently unknown.

Advantages and limitations

The main strength of this meta-analysis is the large sample size. This includes 12 studies of 973 men who are likely to draw relatively accurate conclusions. Expressions across different countries and databases make conclusions solid and credible.

Finally, the quality assessment showed the quality of the methodologies applied in the studies involved.

The first limitation of the study is not to control potential confounders that can affect semen quality. Second, patient age was not reported in all studies, and age is a very important factor in determining male reproductive health.

The time variation between a positive COVID-19 test and semen collection varies from study to study, which represents the third limitation of the meta-analysis. Finally, many studies did not report the severity of the disease that could affect semen parameters.