How does COVID-19 cause people to lose sense of smell? And how many regain it? - ABC News
How COVID-19 causes loss of smell.Since the start of the COVID-19 pandemic, perhaps no symptom has been in the spotlight more than loss of smell.Estimates vary, but it's believed that as many as 96% of COVID-19 patients experience some or total loss -- but it's usually temporary.There are two types of loss of smell that people experience from COVID-19: acute and chronic.A chronic loss of smell happens after a COVID-19 infection has cleared, but, weeks or months later, a person still hasn't regained the sense.A study published Wednesday in the journal Nature Genetics found a COVID-19 patient with a locus, or a specific place of a gene on a chromosome, near two olfactory (sense of smell) genes was linked to anosmia.
Another theory, according to a Harvard Medical School study published in July 2020, is that COVID-19 causes damage to certain cells, called sustentacular cells, that support and assist the olfactory neurons, which identify smells.In addition, a National Institutes of Health study from December 2020 suggested loss of smell may be from COVID-19 causing inflammation and bleeding in the part of the brain -- known as olfactory bulbs -- that controls sense of smell.Sindwani said it's very rare for COVID-19 patients to not regain their sense of smell.Turner said he believes that stories about anosmia have brought a newfound appreciation for sense of smell to the general public