Men may be more vulnerable to COVID-19, the respiratory disease caused by the coronavirus, than women because of their reproductive organs (testicles), a new study has claimed.

Testicle or testis is the male reproductive gland responsible for the production of both sperm and androgens, primarily testosterone.

According to the pilot study, published on MedRxiv, a website on which researchers share their unpublished work, the testicles may habour the novel virus and shield it from the immune system which could make the infection to persist longer in males than females.

The study was carried out by Aditi Shastri, an oncologist at Montefiore Medical Center in the Bronx in company of Jayanthi Shastri, her mother who happens to be a microbiologist at the Kasturba Hospital for infectious diseases in Mumbai.

To arrive at this, the researchers sampled 68 respondents — 48 men and 20 women — living in New York and Mumbai, who had COVID-19.

The respondents were between the age range of three to 75 years old, with their average age being 37.

Findings from the study showed that it took four days to clear the infection in women while men took six days which is 50 percent longer.

It was also found that men took a longer period to recover from the virus than women in the three families that participated in the study.

According to the researchers, this could be due to the large presence of ACE2 protein, or angiotensin converting enzyme 2 in the testes than in the female ovarian tissue.

“We observed that the testes was one of the highest sites of ACE2 expression in 3 independent RNA expression databases (Human Protein Atlas, FAMTOM5 and GETx),” the study said.

“ACE2 was also determined to be highly expressed in testicular cells at the protein levels. Interestingly, very little expression of ACE2 was seen in ovarian tissue.

“Taken together, these observations demonstrate for the first time that male subjects have delayed viral clearance of SARS-CoV2. High expression of ACE2 in testes raises the possibility that testicular viral reservoirs may play a role in viral persistence in males and should be further investigated.”

Some experts have however cast doubt on the hypothesis with Ian Jones, virology professor at the University of Reading, stating that the virus would need to go through the bloodstream before getting to the testis — a development which he said is unusual with the virus.

“The main site of virus replication is the respiratory tract and to reach other sites the virus should have to travel in the bloodstream,” he told Daily Mail.

“This has been reported for the virus but it is not generally what coronaviruses do. Men generally do worse than women in immunological outcomes, possibly the result of only one X chromosome, and I think that this imbalance is more likely behind the differences seen. This work is not peer-reviewed.”

In the same vein, Jonathan Ball, professor of molecular virology at the University of Nottingham, said another study had found no coronavirus in the semen of sufferers.

“In a different study, which again was a preprint and so not peer-reviewed, a small number of males had their semen tested for the presence of the coronavirus while they were recovering from the virus,” he told the news outlet.

“There was also a sample of testes from another patient that had unfortunately died. None of the samples tested positive for the presence of the virus, suggesting that the male genital tract wasn’t an important reservoir for the virus.”

On his part, Derek Hill, a professor of medical imaging at University College London, said there is need for more data before concrete conclusions could be drawn from the study, which is yet to be peer-reviewed.