Autopsies suggest COVID’s smell loss is caused by inflammation, not virus

Although the loss of smell and taste became apparent early in the Pandemic, researchers are still trying to figure out why that happens.

According to a postmortem study out this week, it is the latter. The study which dove deep into the noses, nerves, and brains of 23 people who died of COVID-19 is the most detailed look at the effects on our sniffers. It is good news that inflammation is behind the loss of smell and taste during a bout of COVID-19. It suggests that anti-Inflammatory drugs could prevent damage to the critical senses.

There is a mix of data on the effects of SARS-CoV-2 on our sense of smell. The data suggested that the virus could cause problems with the olfactory nerve. The lost senses could be caused by infections. Some people found that the virus wasn't present in the brain at death.

Nine of the 23 patients who died with COVID-19 had completely or partially lost senses of smell and taste. The researchers looked at the olfactory axons in the nose, blood vessels, and the number of olfactory axons in each patient. They looked at the injuries to the olfactory bulb, the part of the brain where smell signals are received, and found out whether or not the disease was present.

They compared the findings to people who died of other causes and they did not have a loss of smell or taste.

Following the scent

The COVID-19 patients who had altered senses of smell and taste had more injuries to their nose, more damage to their vasculature, and less olfactory axons than the controls.

Some people who had mild COVID-19 had severe injuries to their olfactory bulbs. Only three of the 23 patients had levels of the genetic material present in their olfactory bulbs that were detected. Only one had reported a loss of smell. The other two did not lose taste or smell. The authors concluded that the results suggest the pathology was not caused by direct viral injury.

Previous investigations only relied on routine pathological exams of tissue, and not the in-depth and ultrafine analyses that we conducted.

Losing smell and taste can be caused by this problem and can last for a long time. If inflammation is the main cause of the injury in olfactory structures, we might be able to use anti-Inflammatory agent as the treatment.