Targeted invasion of the testes, cellular interference, inflammation and stress are the four key ways by which COVID-19 may affect fertility.
In a review of COVID-19 studies, researchers discussed how the disease may be affecting men's sexual and reproductive systems.
'Emerging evidence indicates toward the possibility of testicular damage due to COVID-19, which in turn may compromise the fertility potential of such men along with the disruption of the normal production of sex hormones,' Dr Shubhadeep Roychoudhury, co-author of the review, told Inverse.
The review, published in Open Biology, outlines how testes tissue is rich in ACE2 receptors, the virus' favourite entry-point, making the testes susceptible for targeted invasion by COVID-19 infection (see BioNews 1071). The damage of cells in this tissue could have consequences in reproductive health and sperm production.
Inflammation has also been pinpointed as a potential cause of temporary or permanent damage to reproductive tissues. COVID-19 causes immune system overreactions, which may lead to the inflammation of the testicles, with the potential to disrupt the development of sperm cells.
The inflammation of the endocrine tissue as a result of viral interference could lead to disruption in men's testosterone and other sex hormone levels.
Finally, COVID-19 is affecting men's mental health. The increase in the levels of stress could indirectly affect men's reproductive health and well-being. Increased oxidative stress can also disrupt the quality of the sperm by affecting its motility, quantity or shape.
The authors of the review stated how the evidence for the conclusions are still 'preliminary in nature', taking into consideration that there is no long-term, large-scale data that enables a clear prediction on the effects of COVID-19 on male fertility.
'Further clinical trials involving male COVID-19 patients of reproductive age as well as longitudinal studies in paediatric patients will help understand the long-term effects of SARS-CoV-2 infection on testicular functions and spermatogenesis.' said Dr Roychoudhury.