Semen quality remained impaired more than 3 months after a mild COVID-19 infection, according to a small study from Spain involving unvaccinated men.
Testing performed a median 100 days after infection among existing patients at one of six reproductive centers showed lower sperm counts, slower motility, and lower overall sperm quality compared with pre-infection tests taken at the facilities, reported Rocio Núñez-Calonge, PhD, with the UR International Group in Madrid, in a presentation at the European Society of Human Reproduction and Embryology annual meeting in Denmark.
Study participants had various semen parameters significantly worsen after COVID infection:
- Seminal volume reduced by 20% (from 2.5 to 2 mL)
- Sperm concentration was 26.5% lower (from 68 to 50 million/mL of ejaculate)
- Sperm count reduced 37.5% (from 160 to 100 million/mL of semen)
- Semen total motility reduced 9.1% (49.5% to 45%)
- Number of live sperm reduced about 5% (80% to 76%)
Researchers found no differences when comparing semen samples taken less than 100 days after infection to those more than 100 days later.
Núñez-Calonge noted in a press release that it takes approximately 78 days to create new sperm. "We assumed that semen quality would improve once new sperm were being generated, but this was not the case. We do not know how long it might take for semen quality to be restored, and it may be the case that COVID has caused permanent damage, even in men who suffered only a mild infection," she said.
"There are patients whose semen quality still does not improve after 500 days, but we would need to monitor them in the long term," Núñez-Calonge told MedPage Today.
Parviz Kavoussi, MD, of the University at the Texas Health Science Center at San Antonio, commented that seminal quality should be expected to return in about 6 months after mild COVID. He pointed to a study performed in Belgium that showed unvaccinated men with mild illness had impaired seminal values that returned to baseline 3 to 6 months later.
"All illnesses that cause fevers can suppress semen parameters," Kavoussi told MedPage Today. "When the insult has run its course and passed, there are millions of new sperm cells being made in the testicles."
Nevertheless, "it is important for any couple trying to conceive to stay safe/healthy and get their fertility tested especially after any viral illness," Tung-Chin Hsieh, MD, a urologist at the University of California San Diego, told MedPage Today by email.
"Luckily, in this group's men, the decline observed still put them within range for natural conception," said Hsieh, who was not involved with the study.
In the present report, the 45 men studied in Spanish fertility centers ranged in age from 18 to 46 years (median 31). The small sample was limited to individuals with mild COVID-19 disease. Time between their initial sample pre-infection and the post-COVID test was a median 238 days.
As such, findings may not apply to other groups: Kavoussi noted that an autopsy study in men with more severe COVID-19 infections did reveal damage in the testicles related to infection.
How exactly SARS-CoV-2 comes to affect sperm cells is also unclear.
Elevated androgen levels are believed to be a potential mechanism for viral cell entry, Núñez-Calonge said. "Testosterone and androgen receptors, which are co-regulators of ACE2 and TMPRSS2 expression, probably help in the internalization of SARS-CoV-2 in the male reproductive organs."
Núñez-Calonge reported no relevant commercial or financial interests.
European Society of Human Reproduction and Embryology
Source Reference: Núñez-Calonge R, et al "What is the recovery time for sperm parameters in men who have suffered a mild Covid-19 infection?" ESHRE 2023.