COVID-19 og mandlig fertilitet - Opdateringen

Can COVID-19 damage sperm?

A year on from our (first) lockdown, we wanted to refresh this blog, which was originally posted in April 2020, with the latest research into the impact of Covid-19 on sperm health. 

As most of us will know by now, Coronavirus disease 2019 (COVID-19) is a respiratory disease caused by the coronavirus, also called SARS-CoV-2. The most common symptoms of the coronavirus are fever, tiredness, and dry cough. The virus primarily affects the lungs, as we also see in typical influenza during the winter period. Still, the coronavirus can also enter other human organs that possess the entry protein that the virus uses to enter cells (ACE2). 

But should you fear COVID-19 when it comes to male fertility? What research has been done so far and what have we learned? 

Can the effects of Covid-19 impact sperm indirectly? 

In 2020, an early report from Chinese doctors in the Wuhan province suggested that the virus could cause testicular damage. The small report was not enough to draw any conclusions. Therefore, only a few hours after uploading, they deleted it. Since then, there have been further studies on this topic. Although most of them have still been relatively small, they do give some indication as to how Covid-19 could impact sperm health.

A paper published by the journal EClinicalMedicine at the tail end of last year investigated samples from the testis and epididymis (the tube that transports sperm from the testis) of 6 male Covid-19 patients who had passed away and 23 men who were recovering from mild or moderate cases of Covid-19. They did a number of tests, comparing them to men of similar ages who had not had the virus. 

Of the men recovering from Covid, 39% of them had low sperm counts – even though they all had at least one child before contracting the illness. Another interesting discovery was that 61% of the men had an increased number of white blood cells in their semen – which is usually a sign of inflammation – and potentially damaged sperm. Inflammation was also found in the samples taken from men who had died from the virus. 

Research is still inconclusive 

Whilst this study shows us some useful data, it’s important to remember that this was a very small sample size – and the researchers did not know what their sperm count or quality was like before they had Covid-19.

Another recent study, again indicated that Covid-19 could impact sperm directly, however, the results have also been brought in to question by fertility experts including Dr Alsion Campbell, Director of Embryology of the CARE Fertility Group who said ‘Overall, men should not be unduly alarmed by this research”. The prospective, cohort study published in Reproduction focused on 84 previously fertile men who had contracted Covid and tested their sperm at 10-day intervals over 60 days. One of the main issues experts have with the study is that they only tested for 60 days, even though we know that sperm regenerates every 72-90 days. 

Whilst the results may indicate short term damage to sperm cells when battling – and being treated for – Coronavirus, this study fails to show us whether this damage is a concern for the long term. Professor Allan Pacey, Professor of Andrology at the University of Sheffield commented “It would have been more useful to see whether there was a difference at 90 days between the two groups. A paper published last year suggested only a small difference in sperm concentration existed by that time.”

Can the effects of Covid-19 impact sperm indirectly? 

Hormonal disorders 

Recent studies have also highlighted how the impacts of Covid could have an indirect effect on sperm production – particularly via the nervous system. It has been reported that the brain cells (glial cells and neurons) also express ACE 2 receptors, making them a possible target to induce neuronal death for SARS‐CoV‐2. Importantly, the central nervous system plays a critical role in endocrine control and spermatogenesis. Neurons in the hypothalamus secrete a gonadotropin-releasing hormone (GnRH), for example, which triggers the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland. Low levels of GnRH results in decreased FSH and LH, which in turn impacts the function of Sertoli cells and Leydig cells which may induce lower sperm quality. 

Schematic representation of the regulation of HPG axis in healthy and COVID-19 conditions.

Figure A represents the healthy human brain and testes in association with the HPG axis. Figure B represents a SARS-CoV-2 infected human brain and testes with neuroinflammation and dysregulation of the HPG axis in association with reduced steroidogenesis and spermatogenesis due to testicular inflammation and oxidative stress.

Mental Health

Another way in which Covid could indirectly affect sperm health is its impact on our mental wellbeing. Depression and anxiety – which have increased for the general population during the pandemic, and have particularly affected those who have suffered from Covid 19 – are associated with increased levels of cortisol and prolactin – hormones associated with stress. This can have a knock-on effect on male fertility – you can read more about the impact of stress on sperm production here. 

How other viruses impact sperm count and quality

Whilst we wait for more research to be undertaken, we can look at how other, similar infections impact the body. We also know that many different factors both inside and outside the human body affect sperm production. Scientific papers show that infections that increase body temperature have a negative impact on semen quality. This is most likely a response to the increased heat, which harms semen quality. Interestingly, a case study from 2007 showed that fevers could have marked effects on not only semen parameters but also the sperm’s DNA [2][3]. This was a relatively short-term effect, normalizing about two months after the fever.

Genital tract infections can affect sperm directly, while viruses or bacterial infections not entering the genital tract may lower sperm production due to the fever effect [1][3]. One of the most well-known virus-induced infections leading to infertility is mumps. Infection with mumps results in an inflammation of the testicles (orchitis), causing permanent damage.

But are there any permanent effects of COVID-19 on male fertility?

First of all, it is essential to say that there are many people who have become infected with COVID-19 that don’t show any symptoms or feel unwell. Secondly, researchers have so far confirmed that about 80% of those infected with COVID-19 recover from the disease without needing special treatment. At present, it is too early to conclude anything about the permanent effects of a COVID-19 infection on male fertility.

The fever-effect of a coronavirus infection is, if it occurs, most likely a short-term effect. This was demonstrated in a case study from 2007 where the semen parameters return to the pre-fever levels approximately two months after recovering from the fever [3].

What to do in case of any concerns?

You can evaluate your sperm health with a sperm test. An easy and accurate way of doing this could be the ExSeed at Home sperm kit. It includes five sperm tests. This way you can test your current sperm quality and track sperm parameters over time if you have any concerns.