Covid could shrink testicles

Covid could shrink men's testicles and affect their virility as they recover from the coronavirus, microbiology researchers at the University of Hong Kong have found.

Led by microbiologist and government pandemic adviser Yuen Kwok-yung, the team conducted a study on hamsters and found the coronavirus can cause "acute testicular damage, chronic asymmetric testicular atrophy, and hormonal changes" in hamsters even if they only had mild pneumonia.

"In managing convalescent Covid-19 males, it is important to be aware of possible hypogonadism - low sex drive - and sub-fertility," Yuen said. "Covid-19 vaccination can prevent this complication."

The university said the research has been accepted for publication in the medical journal Clinical Infectious Diseases published by Oxford University Press.

Previous studies reported that some Covid male patients suffered from testicular pain, the HKU researchers said.

An autopsy study of males who died from Covid also showed the patients had orchitis - an inflammation of one or both testicles - with much cell damage to them. But coronavirus was not found in these men's semen specimens in the study. In conducting the study, the HKU team followed one group of hamsters infected with Covid-19 and the other group with flu to compare testicular and hormonal changes after infection.

The coronavirus was given to hamsters through their nose, which would only lead to slight pneumonia.

Hamsters only developed mild self-healing pneumonia that could be cured without treatment.

Although the hamsters did not develop severe pneumonia, researchers found their sperm counts and serum testosterone - the male sex hormone that helps male features develop - dropped sharply in four to seven days after infection.

Between 42 and 120 days after infection, researchers found the hamsters' testicles had shrunk, reducing in size and weight. There was also an obvious decrease in the level of sex hormones in the hamsters.

Under microscopic observation, the team discovered the hamsters developed acute inflammation and bleeding in the testicles, necrosis of seminiferous tubules and cessation of sperm production.