Chinese researchers who tested the sperm of men infected with Covid-19 found a minority had the new coronavirus in their semen. According to the researchers, this opened up a small chance the disease could be sexually transmitted, though this claim has been questioned by other academics in the wake of the findings being published.
Such commentators have noted that while viral genome may be found in body secretions, it must be new and active to be infectious. It is unclear from the Chinese study whether the researches found old traces, or active new virus.
The study – by doctors at China’s Shangqiu municipal hospital of 38 men hospitalised with the disease – found that six of them(16%), tested positive for Sars-CoV-2 in their semen.
The researchers said that while the findings were preliminary, and based on only a small number of infected men, more research is needed to see whether sexual transmission might play a role in the Covid-19 pandemic.
“Further studies are required with respect to the detailed information about virus shedding, survival time and concentration in semen,” the team wrote in a study published in the Journal of the American Medical Association.
“If it could be proved that Sars-CoV-2 can be transmitted sexually … [that] might be a critical part of the prevention,” they said, “especially considering the fact that Sars-CoV-2 was detected in the semen of recovering patients.”
Independent experts said the findings were interesting but should be viewed with caution and in the context of other small studies that have not found the new coronavirus in sperm.
A previous small study of 12 Covid-19 patients in China in February and March found that all of them tested negative for Sars-CoV-2 in semen samples.
Allan Pacey, a professor of andrology at Sheffield University in the UK, said the studies should not be seen as conclusive, as there were some technical difficulties in testing semen for viruses. He said the presence of Sars-CoV-2 in sperm did not show whether it is active and capable of causing infection.
“However, we should not be surprised if the virus which causes Covid-19 is found in the semen of some men, since this has been shown with many other viruses such as Ebola and Zika,” he said.
Sheena Lewis, a professor of reproductive medicine at Queen’s University Belfast, stressed that this was a “very small study” and said its findings were in keeping with other small studies showing low or no Sars-CoV-2 in tests of semen samples.
“However, the long-term effects of Sars-CoV-2 on male reproduction are not yet known,” she said.
• This article was amended on 8 May 2020 to expand on the distinction between finding inert Covid-19 in semen, and finding active new Covid-19. A sub-heading mentioning the chance of sexual transmission was changed to attribute this claim to the authors of the study cited in the article.