June 27, 2023 – A COVID infection can reduce sperm count and hinder the ability of sperm to swim for at least 3 months, according to European researchers.
The researchers were surprised that the effects lasted beyond the usual 78 days it takes for the body to make new sperm, even in people who weren’t seriously ill.
“We assumed that semen quality would improve once new sperm were being generated, but this was not the case,” researcher Rocio Núñez-Calonge, PhD, a reproduction expert and professor in Spain, said in a statement. “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.”
The findings were presented Monday at the annual meeting of the European Society of Human Reproduction and Embryology in Copenhagen, Denmark. The study began after Núñez-Calonge and colleagues observed reduced sperm quality after COVID infections in men visiting Spanish fertility clinics. Researchers analyzed semen samples collected from 45 men in Spain before and after they had COVID. The average age of the men was 31 years old.
Compared to pre-infection samples, post-COVID semen volume was down 20%, sperm concentration was down nearly 27%, sperm count was down nearly 38%, and the number of live sperm was down 5%.
The researchers said it has been previously established that COVID affects the testicles and sperm, adding that their new study didn’t uncover what causes the changes. They suspect inflammation and immune system damage, ultimately reducing levels of the male hormone testosterone. The researchers cautioned that it was just a theory because they did not measure hormone levels as part of their study.
The chairperson of the professional group that hosted the conference said the changes may not impact the ability to conceive a child.
“It’s important to note that the semen quality in these patients after a COVID infection is still within the World Health Organization’s criteria for ‘normal’ semen and sperm,” said Carlos Calhaz-Jorge, MD, PhD, a professor of obstetrics and gynecology at the University of Lisbon Medical School in Portugal who wasn’t involved in the study. “So, it is unclear whether these reductions in semen quality after a COVID infection translate into impaired fertility, and this should be the subject of further research.”