A 45-year-old British man has been left with permanent hearing loss after developing Covid-19.
UK doctors say it is the first such case they have seen linked to the pandemic coronavirus.
Although rare, sudden hearing loss can follow other viral infections, such as flu.
The ear-nose-and-throat experts told BMJ Case Reports journal steroid drugs could help avoid this damage if given early enough.
The patient, who has asthma, had been admitted to a London hospital with Covid-19 symptoms and transferred to intensive care after struggling to breathe.
Tests confirmed he had coronavirus and he was put on a ventilator machine.
He also needed various drugs and a blood transfusion before beginning to recover and coming off the ventilator 30 days later.
But a week after the breathing tube was removed and he left intensive care, he noticed tinnitus (a ringing or buzzing noise) followed by sudden hearing loss in his left ear.
A hearing test suggested the loss was linked to damage to the hearing nerve, the middle ear, or both, rather than inflammation or a blockage to the ear canal.
Doctors could find no explanations for his hearing problem, other than his recent Covid-19 illness.
They gave him steroid tablets as well as injections into the ear, which helped a little, but he has some irreversible hearing loss.
"Given the widespread presence of the virus in the population and the significant morbidity of hearing loss, it is important to investigate this further," the team, from University College London and the Royal National Throat, Nose and Ear Hospital, said
The virus is thought to enter and infect a particular type of cell found in the lungs, by zoning in on a surface receptor they possess.
The researchers say this same receptor is found on the cells that line the middle ear.
And they are recommending medics look out for hearing complications in Covid-19 patients and refer any with sudden hearing loss to an expert for urgent care.