Semen quality decreases in the long term after suffering from mild COVID

Three years of pandemic and millions of people infected by the SARS-CoV-2 coronavirus have provided a huge amount of data for scientists to investigate this infectious disease and its long-term sequelae, known as persistent or prolonged COVID and which is characterized by a diversity of symptoms that many people experience with greater or lesser intensity after passing the infection.

Many organs and systems of the body have been affected by this virus, even after the patient has overcome the initial illness, and now a new study has analyzed how COVID-19 has affected sperm concentrations and quality of men after suffering a mild coronavirus infection and when enough time had passed – three months in this case – for new semen to have been produced.

The results have been presented at the 39th annual meeting of the European Society for Human Reproduction and Embryology (ESHRE) and show that more than three months after suffering a mild COVID infection, men have lower sperm concentrations and fewer sperm that can swim than was observed in pre-illness samples.

Half of the men had total sperm counts that were 57% lower after COVID compared to their pre-COVID samples

The teacher Rocío Núñez Calongeembryologist, scientific director of the UR International Group and professor in the Master’s Degree in Reproduction at the Complutense University and the Spanish Fertility Society, has declared that after a average 100 days after SARS-CoV-2 infectionthere did not appear to be an improvement in sperm quality and concentration, even though new sperm would have been produced in that time.

Speaking to SMC Spain, Professor Núñez Calonge explained: “Several studies show the impact of SARS-CoV-2 on the health of infected men compared to fertile controls and the negative effect on semen parameters. However, there are few studies that study the effect of COVID-19 in semen samples from patients before and after infection, in men with mild infection, as well as the long-term outcome. In most of the works it is assumed that, if the virus affects the testicle, and therefore the production of spermatozoa, once a cycle of spermatogenesis (formation of the sperm), which lasts approximately 70 days, the normalization of the seminal parameters will take place”.

“We assumed that semen quality would improve once new sperm were generated, but it didn’t. We do not know how long it may take to restore semen quality and COVID may have caused permanent damageeven in men who suffered only a mild infection ”, warned the expert during the presentation of the study results at ESHRE.

Motility and total sperm count, the most affected

Professor Núñez Calonge and her colleagues observed that the semen quality of some men attending clinics in Spain for assisted reproductive treatment was worse after COVID infection than before infection, even though they had recovered and the infection had followed. they had suffered had been mild, and for this reason they decided to investigate whether COVID had influenced the drop in quality.

“Since it takes approximately 78 days to create new sperm, it seemed appropriate to assess semen quality at least three months after recovery from COVID,” Núñez Calonge said. Between February 2020 and October 2022, the researchers recruited for the study 45 men attending six reproductive clinics in Spain. They all had a confirmed diagnosis of mild COVID and the clinics had analysis data on semen samples taken before the men became infected.

Another semen sample was taken between days 17 and 516 after infection. The average age of the men was 31 years, and the amount of time between pre-COVID and post-COVID samples was a median of 238 days. The researchers analyzed all samples taken up to 100 days after infection and then analyzed a subset of samples taken more than 100 days later.

They found a statistically significant difference in semen volume (20% less than 2.5 to 2 milliliters), sperm concentration (26.5% less than 68 to 50 million per mL of ejaculate), sperm count (37.5% less than 160 to 100 million per milliliter of semen), total motility, that is, being able to move and swim forward (9.1% less, from 49% to 45%) and the number of live sperm (5% less, from 80% to 76%).

The most affected parameters were motility and total sperm count, as pointed out by Professor Núñez-Calonge. Half of the men had total sperm counts that were 57% lower after COVID compared to their pre-COVID samples. Sperm shape was not significantly affected.

When the researchers looked at the group of men who provided a sample more than 100 days after COVID, they found that sperm concentration and motility remained unimproved despite the time elapsed. “The ongoing effect of COVID infection on semen quality in this latter period may be caused by permanent damage due to the virus, even in mild infection. We believe that physicians should be aware of the harmful effects of the SARS-CoV-2 virus on male fertility. It is especially interesting that this decrease in semen quality occurs in patients with mild COVID infection, which means that the virus can affect male fertility without men presenting any clinical symptoms of the disease,” said Núñez Calonge. .

Temporarily or permanently affected male fertility

It is known that the SARS-CoV-2 virus can affect the testicles and sperm, but the mechanism is still unknown. Professor Núñez Calonge says that the inflammation and damage to the immune system seen in patients with prolonged COVID could be involved. “The inflammatory process can destroy germ cells by infiltrating white blood cells involved in the immune system and reduce testosterone levels by affecting the interstitial cells that produce the male hormone,” he said.

“It is worth mentioning that the deterioration of semen parameters may not be due to a direct effect of the SARS-CoV-2 virus. It is likely that there are additional factors that contribute to the decline in semen parameters in the long term, but whose identity is currently unknown. Furthermore, we did not measure hormone levels in this study: intense changes in testosterone, a key factor involved in the male reproductive healthin male patients infected with COVID”.

“These two findings, the affectation of semen quality in men who have suffered a mild infection by covid-19, and that these effects can be long-term, are of great importance when considering male reproductive health. Although more studies are necessary to find out the mechanisms by which this damage is induced and persists over time, these patients who have suffered the infection should be studied, especially those who have a reproductive desire”, concludes Núñez Calonge in statements to SMC Spain.

The President of ESHRE, Professor Carlos Calhaz-Jorge from the Centro Hospitalario del Norte de Lisboa and the Hospital de Santa María de Lisboa (Portugal), who has not participated in this research, opines: “This is an interesting investigation by Professor Núñez -Calonge and his colleagues and shows the importance of long-term follow-up of the fertility of patients after a COVID infection, even if it is a mild infection. However, it is important to note that semen quality in these patients after a COVID infection is still within the World Health Organization criteria for ‘normal’ semen and sperm. Therefore, it is not clear whether these reductions in semen quality following COVID infection will translate into impaired fertility and this should be the subject of future research.”

Dr. Ying Cheong, Professor of Reproductive Medicine at the University of Southampton, explained in statements to the Science Medica Center that Núñez Calonge and his colleagues “conclude that sperm parameters are poorer after infection and recovery time it may be longer than 100 days”, although in his opinion: “The results should be interpreted with caution, as the post-COVID sperm collection period was not standardized and ranged from 17 to 516 days”.


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