“We hypothesize that potential symptoms could be changes in the character and quality of hearing, balance, ringing, or sensations of fullness or pressure,” C. Matthew Stewart, MD, associate professor of head and neck surgery at the Johns Hopkins University School of Medicine, told Newsweek. In June, a study in Iran examined six COVID-19 patients under 40 with mild clinical symptoms—all of them had mild-to-moderate hearing loss in one ear, neurobiology postgraduate student Shin Jie Yong points out. For this new study, however, Stewart and other doctors in John Hopkins Hospital autopsy research program conducted autopsies on three patients who tested positive for COVID-19. Two of the three patients showed the presence of coronavirus in the mastoid—a honeycomb-like bone in the skull located directly behind the ear, according to Mount Sinai hospital—or middle ear. Two of the mastoids and three of the middle ears examined tested positive for COVID infection, the study found. Newsweek notes that Bradley W. Kesser, MD, of the University of Virginia Department of head and neck surgery, confirms that the study identifies a new potential route of coronavirus transmission. In an article for JAMA Otolaryngology–Head & Neck Surgery, Kesser writes: “By isolating SARS-CoV-2 from the middle ear and mastoid in postmortem ears and mastoid cavities in patients succumbing to COVID-19, the study … offers proof of principle of the virus’ ability to access the middle ear and/or mastoid, documents another potential route of SARS-CoV-2 transmission, and addresses the implications for protection of health care workers caring for patients with ear disease.“ae0fcc31ae342fd3a1346ebb1f342fcb RELATED: For more up-to-date information, sign up for our daily newsletter. To that latter point, Stewart notes the findings also indicate that surgeons performing procedures on these parts of the body are at an increased risk of contracting COVID-19 if the patient is infected. Stewart explained to Newsweek that the techniques and medical tools—hand-held drills, for example—used in these surgeries are not all that safe during the pandemic due to the fact that they spur the release of airborne droplets and particles from the patient being operated on. And for more less well-known coronavirus signs, check out 6 COVID Symptoms That Are Right in Front of You.