One day in July, while Meredith Harrell was walking from her backyard into the house, her right ear suddenly started to ring.

She realized that, other than the ringing, she couldn't hear anything out of that ear.

"It was like someone flipped a switch," she said.

Harrell's hearing loss was a mystery until about a week later, when she took a COVID-19 test. It was positive. 

Even though she never felt sick, an otologist -- a doctor who specializes in hearing -- explained to Harrell that the virus was likely the culprit.

Viruses such as measles, mumps and meningitis are known to sometimes cause sudden hearing loss, and there's growing evidence that the novel coronavirus should be added to the list.

"We're hearing more and more that people have hearing loss as part of their COVID infection," said Dr. Matthew Stewart, associate professor of otolaryngology at Johns Hopkins Medicine.

There are no statistics on how common it is for people who've had COVID-19 to experience hearing loss, but a few small studies point to a possible link.

A team in Manchester, England, asked COVID-19 patients eight weeks after they'd been discharged from the hospital whether they'd experienced any hearing changes or ringing in their ears. Of the 138 patients in the study, published in the International Journal of Audiology, 13 per cent said yes.

Doctors can't say for sure that the virus attacks the inner ear. Doing a biopsy of the inner ear can be dangerous, as it risks damaging the tissue.

Stewart and his colleagues performed procedures on the bodies of three people who had died after a COVID-19 infection to see if they could find the virus in the inner ears.

In two of the three cadavers, they found the novel coronavirus in the middle ear and mastoid bone in the skull, which is located just behind the ear. The study was published in JAMA Otolaryngology -- Head and Neck Surgery.

Stewart said while other viruses have been known to cause sudden hearing loss, "personally I'm suspicious that [the novel coronavirus] has the potential to be worse."

He said the reason is that the coronavirus is known to cause blood clots in other areas of the body, and he thinks that could be happening in the "extremely small blood vessels" in the inner ear.

Kevin Munro, an audiological scientist who co-authored the study in Manchester, said he thinks that theory makes sense.

"The capillaries in the inner ear are the smallest in the human body, so it wouldn't take much to block them," he said.

Munro and his team at the University of Manchester are planning larger studies on COVID-19 and hearing loss.

Until then, they're not sure why it seems like some COVID-19 patients develop hearing loss while others don't.

Munro and Stewart said the treatment is high doses of oral steroids.

They seem to have helped Liam, a 23-year-old student, who lost 70-80 per cent of the hearing in his left ear after a COVID-19 infection.

Liam contracted COVID-19 in June, and had a fever, headache and was exhausted for weeks. After he started feeling better, he suddenly lost his hearing and had tinnitus, or ringing in the air.

After a round of steroids, he said he can now hear everything except high tones. The ringing has persisted, and he said his doctors tell him it might never go away.

"It's really dreadful," said Liam, who asked that his last name not be used to protect his privacy.

Steroids did not work for Harrell. She said her doctors tell her she's unlikely to get her hearing back in her right ear, and will be fitted soon with a hearing aid. The tinnitus in that ear might not stop, either.

Harrell thinks back to how she contracted COVID-19. It was late June, and a friend came over for a visit. She said they spent most of the time outside.

That friend called a few days later to say he'd been exposed to someone with COVID-19.

Harrell, 42, said her husband and children also tested positive for the virus. Her husband had tightness in his chest for a few days, and her children, ages 9 and 10, had no symptoms.

"I wasn't sick, but I still had consequences," she said. "I hope people get the message that this is no joke."