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More than three months after contracting a mild COVID infection, men have lower sperm concentrations and fewer sperm that can swim, according to new findings presented at the 39th annual meeting of the European Society of Human Reproduction and Embryology (ESHRE).
Professor Rocio Núñez-Calonge, Scientific Advisor at UR International Group at the Scientific Reproduction Unit, Madrid (Spain), said that after an average of 100 days after SARS-CoV-2 infection, there appeared to be no improvement in the quality and concentration of the semen. even though new sperm would have been produced in that time.
“There have been previous studies showing that sperm quality is compromised in the short term after a COVID infection, but to our knowledge none have followed men over an extended period of time,” she said. “We assumed sperm quality would improve once new sperm were generated, but this was not the case. We don’t know how long it could take for sperm quality to recover and COVID may have caused permanent damage even in men who have only had a mild infection.”
prof. Núñez-Calonge and colleagues had noticed that in some men visiting clinics in Spain for assisted reproduction treatment, sperm quality was worse after COVID infection than before infection, even though they had recovered and the infection was mild. So they decided to investigate whether COVID had influenced the decline in quality.
“Since it takes about 78 days to make new sperm, it seemed appropriate to evaluate sperm quality at least three months after recovery from COVID,” said Prof. Núñez-Calonge.
Between February 2020 and October 2022, the researchers recruited 45 men attending six reproductive clinics in Spain for the study. They all had a confirmed diagnosis of mild COVID and the clinics had data from analysis of semen samples taken before the men were infected.
Another semen sample was taken between 17 and 516 days after infection. The median (mean) age of the men was 31, and the amount of time elapsed between the pre- and post-COVID samples was a median 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 (down 20% from 2.5 to 2 milliliters), sperm concentration (down 26.5% from 68 to 50 million per ml of ejaculate), sperm count (down 37.5% from 160 to 100 million per milliliter of semen), total motility, ie being able to move forward and swim (9.1% dropped from 49% to 45%) and the number of live sperm (dropped 5% from 80% to 76%).
prof. Núñez-Calonge said motility and total sperm count were most severely affected. Half of the men had total sperm counts that were 57% lower post-COVID compared to their pre-COVID samples. Sperm shape was not significantly affected.
When the researchers looked at the group of men who delivered a sample later than 100 days after COVID, they found that sperm concentration and motility had still not improved over time.
“The continued effect of COVID infection on sperm quality in this later period may be due to permanent damage from the virus, even with mild infection. We believe that clinicians should be aware of the detrimental effects of the SARS-CoV-2 virus on male fertility. It is particularly interesting that this decline in sperm quality occurs in patients with mild COVID infection, meaning that the virus can affect male fertility without the men showing any clinical signs of the disease,” said Prof. Núñez-Calonge.
It is known that the SARS-CoV-2 virus can affect the testes and sperm, but the mechanism is still unknown. prof. Núñez-Colange says there may be inflammation and damage to the immune system seen in patients with long-term COVID.
“The inflammatory process can destroy germ cells by infiltrating the white blood cells involved in the immune system, and lower testosterone levels by affecting the interstitial cells that produce the male hormone,” she said.
“It should be mentioned that the impairment of sperm parameters may not be due to a direct effect of the SARS-CoV-2 virus. There are likely additional factors that contribute to the long-term decrease in sperm parameters, but of which the identity is currently unknown.” In addition, we did not measure hormonal levels in this study: intense changes in testosterone, a key player in male reproductive health, have previously been reported in COVID-infected male patients.”
The researchers plan to continue studying the men to measure both sperm quality and hormonal status over time. They believe there should be more research into men’s reproductive functions after a COVID infection to see if their fertility is temporarily or permanently affected.
The President of ESHRE, Professor Carlos Calhaz-Jorge of the Northern Lisbon Hospital Center and the Hospital de Santa Maria in Lisbon (Portugal), was not involved in this research. He noted: “This is interesting research by Prof. Núñez-Calonge and her colleagues and demonstrates the importance of long-term follow-up of fertility patients after a COVID infection, even if it is a mild infection. However, it is important to notice that sperm quality in these patients after COVID infection still falls within the World Health Organization criteria for ‘normal’ semen and semen, so it is unclear whether this reduction in sperm quality after COVID infection translates into reduced fertility and This would be the subject of further investigation.”
More information:
Presentation No: O-020, “What is the recovery time for semen parameters in men who have acquired a mild Covid-19 infection?” presented by Professor Rocio Núñez-Calonge, Session 04: Factors affecting sperm (dys)function, Room D1, 11:15 am CEST, Monday 26 June 2023.
Quote: Men experience long-term decline in semen quality after COVID infection, study results (2023, June 26) Retrieved June 26, 2023 from https://medicalxpress.com/news/2023-06-men-long-term-semen-quality -covid.html
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