New research has shown that men experience a substantial and lasting decrease in semen quality after contracting COVID-19, including mild cases. The study found that both sperm concentrations and the number of motile sperm significantly decrease for over three months after recovering from a mild infection.

Mild COVID-19 infection can affect semen quality in the near-term

Although the body produces new sperm during this period, there is no observed improvement in sperm quality or concentration, as Professor Rocio Núñez-Calonge, a scientific advisor at UR International Group in Spain, reported.

Prof. Núñez-Calong said semen quality is adversely affected in the short term after a COVID infection. However, there is limited information about the long-term effects. Researchers believed semen quality would improve as new sperm were produced, but that was not observed. The duration for semen quality restoration is unknown, and it is possible that COVID could cause permanent damage, even in individuals with mild infections.

Researchers conducted the study in Spain and initially observed a decline in semen quality in some men seeking assisted reproduction treatment after experiencing a mild COVID-19 infection. The researchers recruited 45 men from six reproductive clinics in Spain between February 2020 and October 2022 to further examine this decline. All participants had confirmed mild COVID-19 infections, and the clinics had data on semen samples collected before the participants became sick. Additional semen samples were collected between 17 and 516 days after the infection.

COVID-19 affects sperm count and motility

In a study, researchers examined samples collected within 100 days of infection and a smaller set of samples taken after 100 days. They found a 20% decrease in semen volume, 26.5% in sperm concentration, 37.5% in sperm count, and 9.1% in total motility.

The study conducted by Prof. Núñez-Calonge found that COVID-19 significantly impacted total sperm count and motility. About half of the men examined had a 57 percent lower total sperm count after being infected with COVID-19 compared to their pre-infection samples. However, the shape of the sperm was mostly unaffected.