Coronavirus transmission via semen ‘cannot be ruled out despite little evidence’

Coronavirus transmission through semen cannot be completely ruled out – even though there is currently very little evidence of Covid-19 infections occurring via the bodily fluid, an expert has said.

Professor Allan Pacey, an andrologist at the University of Sheffield and former chairman of the British Fertility Society, also said that there is a “plausible reason” to be concerned about fertility issues in men affected by Sars-Cov-2, the virus that causes Covid-19.

But he added that initial data from scientific studies “does not really support the hypothesis that either reproductive hormones or sperm quality are affected” by the virus and “other aspects of testicular function remain to be evaluated”.

Prof Pacey said he looked at 14 scientific papers which focus on Sars-Cov-2 and male fertility.

One such study, which is yet to be peer-reviewed, involved a small group of men who were admitted to a hospital in China with Covid-19 and tested positive for Sars-Cov-2 in their semen.

Meanwhile, there have been other small studies suggesting that sperm counts of Covid-19 infected men temporarily declined after they were diagnosed with the disease.

But Prof Pacey said studies such as these have caveats and should not be seen as conclusive as they “looked at a remarkably small number of men”.

Speaking at a virtual conference on fertility, genomics and Covid-19, organised by the Progress Educational Trust (PET), Prof Pacey said: “There is, understandably, I think, very little epidemiological data at a population level, or for men intending for assisted conception, and I think that is a group that we still need to closely look at, because if men are at the infertile end of the spectrum, then maybe, they are likely to suffer greater damage than men who are in the normal range.”

He added: “There is little current evidence that Sars-Cov-2 is transmitted in semen, but I don’t think I can completely rule it out, so we still need to carry on with further studies.”

Prof Pacey, who is also the editor-in-chief of the journal Human Fertility, said that despite little evidence that Sars-Cov-2 can be detected in semen, there has been some analysis which “suggests that it might be present in the testicles”.

He added: “Perhaps that shouldn’t be a surprise because we know all kinds of viruses do sequester themselves in the testicles – Ebola, dengue fever, zika.

“The testes is an immuno-privilege site and viruses can, kind of, hang around there for quite some time without causing any clinical pathology to the individual.”

Meanwhile, Ashley Moffett, emeritus professor of reproductive immunology at the University of Cambridge, who was also speaking at the conference, said that there is no evidence that pregnant women are more seriously at risk of death from Covid-19 infection.

But she added that, at the moment, it is too early to recommend Covid-19 vaccines for mothers-to-be until more data becomes available.

Prof Moffett said: “The vaccine trials did not include pregnant women so this will have to wait until we have that information.”