Research carried out on 120 men in Belgium by local academics showed that semen is "not infectious" with COVID-19 and therefore cannot be transmitted through sexual contact.

But the study warns: "Couples with a desire of pregnancy should be warned that sperm quality after COVID infection can be suboptimal."

The researchers, whose work has not been peer-reviewed, estimate that sperm levels should be back to normal after three months.

"Sperm quality parameters were most severely damaged when assessed during the first month," they said, adding that damage was "less pronounced" after the first month and "almost normal" after two months.

The academics are working on a follow-up study to see if damage to sperm count could be permanent in a small minority of men.

Scientists all over the world are still waiting for data on whether the new, more transmissible Omicron variant causes less or more severe disease than Delta.