12 Recent Findings About Long COVID That Researchers Are Tracking

9. Sensory System Impacts - Smell, Taste, and Beyond

The loss of smell and taste (anosmia and ageusia) were among the first recognized symptoms of COVID-19, but recent research has revealed that sensory dysfunction in Long COVID extends far beyond these initial observations and can involve multiple sensory systems with complex, long-lasting effects. Comprehensive studies of smell and taste recovery have shown that while some patients regain normal function within weeks or months, a significant percentage continue to experience persistent sensory dysfunction that can profoundly impact quality of life. Advanced research using olfactory testing and brain imaging has revealed that COVID-19 can cause damage to olfactory neurons and the olfactory bulb in the brain, potentially explaining why recovery can be slow and sometimes incomplete. Perhaps more concerning, many patients develop parosmia – a distortion of smell where familiar odors become unpleasant or completely altered – which can make eating and daily activities extremely challenging. Studies have also documented phantom smells (phantosmia), where patients perceive odors that aren't actually present, and taste distortions that can make previously enjoyed foods taste metallic, bitter, or completely foreign. Recent research has expanded beyond smell and taste to investigate other sensory impacts of Long COVID, including visual disturbances such as blurred vision, light sensitivity, and eye pain that can persist long after acute infection. Some patients report auditory symptoms including tinnitus (ringing in the ears), hearing loss, and hyperacusis (increased sensitivity to sound). Neurological studies suggest these diverse sensory symptoms may result from viral effects on cranial nerves, brain inflammation, or autoimmune responses that target sensory processing centers. The recognition of these widespread sensory impacts has led to the development of specialized rehabilitation programs that include smell training, taste rehabilitation, and multisensory therapy approaches designed to help patients adapt to their altered sensory experiences.