Flu season typically wreaks havoc on my male fertility practice. A solid flu, complete with fevers and body aches, drops sperm counts like a brick. But only temporarily. Things usually bounce back within 2-3 months. In contrast, the common cold doesn’t affect male fertility. This leads us to believe that the fever’s the thing. Fevers heat up the body and testicles and bring sperm production to a grinding halt. This is the same concept behind the effects of hot baths and tubs on sperm counts. Heat hurts male fertility.
Ah, but what about the novel COVID-19 virus that is now uprooting our lives? Can it impact male fertility the way it has the stock market? Like any other seasonal virus, COVID-19 will temporarily impair sperm production if it is associated with fevers. But, there has also been recent mention (and then immediate retraction) in the Chinese press of the “theoretical possibility” that male fertility could be heavily impacted with COVID-19 since the virus infects us through the same receptor (ACE2) that is found in the testicle. My opinion: True, true, unrelated. The testicles share hundreds of the same receptors found elsewhere in the body, including taste, so the relevance of this factoid is questionable at best. Besides, we haven’t any evidence of a permanent impact of a seasonal flu virus on male fertility since time immemorial. Although no cause for worry, it does merit more research and less rumor.
Virulent Viruses and Coronials
In fact, we can count on one hand the number of viral infections that can permanently affect male fertility: the mumps virus, which doesn’t cause the flu. But to permanently affect fertility, mumps has to infect boys at puberty when the testicles are actively growing and it also has to “drop” and infect the testicles themselves, which occurs in 10-20% of peripubertal mumps cases. That means that having mumps earlier in childhood has no impact on future fertility. Another virus that might affect male fertility is the Zika virus, a flu virus transmitted by mosquitoes. The latest epidemic of Zika was in 2016 in the Southern hemisphere. You probably remember this virus because of fetal birth defects associated with Zika-infected pregnant women. During that outbreak, research was done on mice to see if Zika might impair male fertility after the infection resolved, and it did. However, the efficiency of this occurrence in mice is entirely unknown and this same issue has not been found in Zika-infected men. Just so you know, there are also no documented cases of testicular infections during the current COVID-19 pandemic.
So, we expect the COVID-19 virus to affect male infertility temporarily, similar to the seasonal flu. Given the stay-at-home restrictions around the world, this pandemic may even be a boost for human fertility, leading to a whole new batch of next-gen “coronials!”