COVID-19 may be more than just a respiratory illness after researchers found its effects on the male’s reproductive organ. The virus could lower testosterone levels and reduce sperm size and count, according to a new study from the University of Hong Kong.

The Study

In the research published Feb. 18 via Oxford Academic, the team of researchers presented their findings after experimenting to find out how intranasal or testicular inoculation of the virus would affect the testicles of golden Syrian hamsters.

The team investigated the virological, pathological, and immunological changes in the testes of the hamsters infected with the original strain of SARS-CoV-2 and its variants. They found that aside from the usual respiratory tract infection, the virus caused a depletion in sperm count and testosterone.

Eventually, they observed a reduction in testicular size and weight and other varying complications, such as testicular inflammation, hemorrhage, and necrosis. They noticed similar testicular changes in both intranasal and direct testicular inoculation with the delta and omicron variants.

The damage to the testes manifested as early as four to seven days after being infected with SARS-CoV-2. The hamsters were killed between one and 120 days after infection, and their testicles were examined for changes.

The Takeaway

The researchers also experimented on vaccinated hamsters to see how they fared against the virus and found that the vaccinated ones did not exhibit testicular damage.

It is important to pay attention to the effects of COVID-19 on the testicles to bring awareness of possible hypogonadism (low sex drive) and fertility issues in human males after battling coronavirus infection, the team said.

Lead author Kwok-Yung Yuen told The Standard that their study reiterated the need to get vaccinated against COVID-19 amid the ongoing pandemic because “vaccination can prevent this complication.”

COVID studies and experiments commonly use hamsters since their bodies’ reactions to respiratory viruses are similar to humans. Experiments on hamsters “provide useful information about the profession of virus pathogenesis,” Richard J. Sugrue, associate professor of virology at Singapore’s Nanyang Technological University, told Vice World News.