June 27, 2023 – COVID infection can reduce sperm count and impair sperm swimming ability for at the least three months, in line with European researchers.
The researchers were surprised that the effect lasted longer than the standard 78 days it takes the body to provide recent sperm, even in individuals who weren't seriously sick.
“We assumed that sperm quality would improve once new sperm was generated, but that was not the case,” said researcher Dr. Rocio Núñez-Calonge, a reproductive expert and professor in Spain, in an announcement. “We do not know how long it might take for sperm quality to recover, and it may be that COVID has caused permanent damage, even in men who only suffered a mild infection.”
The results were presented on Monday on 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 attending Spanish fertility clinics. The researchers analyzed semen samples collected from 45 men in Spain before and after their COVID illness. The average age of the boys was 31 years.
Compared to pre-infection samples, post-COVID sperm volume decreased by 20%, sperm concentration decreased by almost 27%, sperm count decreased by almost 38%, and live sperm count decreased by 5%.
The researchers said COVID has previously been found to affect the testes and sperm, adding that their recent study didn't reveal what causes the changes. They suspect inflammation and damage to the immune system, which ultimately lowers levels of the male hormone testosterone. The researchers cautioned that this is simply a theory, as they didn't measure hormone levels as a part of their study.
The chairman of the skilled group that hosted the conference said the changes may not affect the power to have children.
“It is important to note that the semen quality of these patients after COVID infection is still within the World Health Organization criteria for 'normal' semen and sperm,” said Carlos Calhaz-Jorge, MD, PhD, professor of obstetrics and gynecology on the University of Lisbon's Faculty of Medicine in Portugal, who was not involved within the study. “So it is unclear whether these reductions in semen quality after COVID infection lead to impaired fertility, and this should be the subject of further investigation.”