There is growing speculation as to whether testicles, the primary male reproductive organs, could be affected by COVID-19 following recent red flags raised by researchers in the reproductive field.
The Science
COVID-19 works by binding to ACE2, a specific protein that allows the virus to infect human cells. ACE2 is present in many cell types, including the lungs, heart, kidneys and liver, however it is highly expressed in the testicles. This gives reason to believe COVID-19 may have an effect on the sperm producing cells found in these organs.
The Studies
There are studies being conducted looking into the effect of COVID-19 on male fertility. However, they remain in the early stages due to small sample size and lack of peer reviews.
A recent study undertaken in Wuhan compared 81 males that had contracted Covid-19 with 100 males who had not. This revealed hormones involved in reproduction were affected, however, levels of testosterone were not.
Other small studies in China suggested there was no effect on male fertility due to the lack of a second protein needed for the virus to enter the ACE2 protein.
Male fertility is often affected by the contraction of viruses, such as Hepatitis B and Mumps
Since COVID-19 is a strain of SARS, it is interesting to note previous studies during the SARS outbreak in 2002 found that orchitis (inflammation of the testicles) was a recognised complication of the virus. This could lead to long term effects on testicular function, therefore affecting male fertility.
What does this mean for male fertility?
In light of this research there is a theoretical possibility that following a COVID-19 infection men could be left with testicular damage and therefore reduced fertility. For men who already have fertility issues, the effects of this could be of greater concern.
Short Term
We may not know too much about all the effects of COVID-19 on human health but it is reasonable to assume that because of the high and sustained fever caused by the virus, male fertility may be temporarily affected.
The internal body temperature, including that of the testicles, will be higher than usual in someone fighting COVID-19. This can damage the sperm being held there at the time due to overheating. The impact of this should be temporary and not affect future sperm, allowing fertility to return to normal with the new generation of sperm.
The binding of the virus to the ACE2 protein may cause temporary changes to the count, motility and morphology of sperm in a male who has recently contracted COVID-19. However, there is a growing belief that these effects will only last as long as the period it takes for the sperm to regenerate (~3 months) after the virus has been eradicated.
Long Term
Much more research is needed focussing on the long lasting effects of COVID-19 on people’s health, including male fertility. Since strains of SARS in the past have caused inflammation of the testicles it is possible COVID-19 may also do this. This could have a long term impact on testicular function and thus male fertility.
It is important to note this is still speculation as there have not yet been studies showing the COVID-19 virus present in the testicles or semen. There is still much more to be learnt about the future impact of COVID-19 on health before conclusions are drawn but this is certainly a topic to keep an eye on.
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