Coronavirus may lead to infertility in men — even if they only suffer a mild form of the disease, a doctor has claimed.
Sperm counts of infected men halved 30 days after they were diagnosed with Covid-19, according to an Israeli study.
And Dr Dan Aderka from the Sheba Medical Centre in Tel Aviv, also alleged sperm motility — or its ability to move by itself — was also hampered.
But scientists insist the truth on whether Covid-19 permanently damages fertility is still murky, and that even flu causes a temporary drop in sperm counts.
Coronavirus may cause infertility in men even if they suffer mild forms of the disease, it has been claimed. (stock image)
Several studies have previously suggested that an infection with the virus could impact fertility, but there is yet to be any firm proof to back up the claim.
Some blame fever for a drop in sperm production - as the cells require 34C (93.2F) for their production - although it is thought their numbers can bounce back post-infection.
Several large studies are currently underway to identify whether the virus impacts fertility.
One, backed by the National Institute of Health (NIH), will examine the medical records of more than 20,000 pregnant women to determine differences between them and 1,500 women who were pregnant and had coronavirus.
Their aim is to understand how the virus affects maternal health and how changes in access to healthcare due to the pandemic are impacting pregnant women.
An ASPIRE study is also underway, which will look at pregnancies during the first trimester - when the baby's organ systems form and the placenta develops.
It hopes to understand the impact of Covid-19 on this critical early stage of development.
The Jerusalem Post, which reported the research claimed it was published in the journal of Fertility and Sterility, and it claimed the changes were seen in men with mild cases but did not address how many people were involved.
However, the journal today hit back and said it had no record of Dr Aderka submitting the elusive paper.
Because no journal has yet to publicly release the study it means scientists from around the world have yet to be able to point out obvious flaws in its method.
Scientists studying the effect of coronavirus on fertility have, however, made similar claims in the past.
But doctors insist reports of men having lower sperm counts are likely down to them having had a fever — a tell-tale symptom of coronavirus.
This, scientists say, makes it harder for the body to produce sperm. They also argue that production can bounce back after an infection has passed.
Professor Allan Pacey, an andrologist at the University of Sheffield and former chair of the British Fertility Society, told MailOnline