"The pressure of suffering is enormous"

That is an interesting question. It is the interaction of different odor molecules that makes up the typical smell of bananas, for example. It is often the case that odor molecules can activate different olfactory receptors in our nose. The pattern of activations that results is then interpreted by the brain as, "That's banana smell." Now imagine that in this patterned tapestry of neurons, every third one fails, and the result is no longer "banana." The signal to the brain is suddenly quite different. My hypothesis is therefore that parosmias are simply malfunctions and not warning mechanisms.  

Since our first conversation, do you know more about the time periods when the sense of smell returns to normal?

In our studies, we specifically looked for participants who were acutely ill or had been ill in the last 14 days. So we can only say something about a longer period of time to a limited extent. In the recovered group, smell and taste disturbances were still present in about half of the cases. We fear: Those who are not yet healthy after 30 days are likely to have their impairments last longer. In addition, we asked a sample of our participants again after a few months how their symptoms had developed. We started this a month ago, and we already have a few thousand responses. We hope that this and other parallel studies will provide us with more concrete information.

Are there also COVID-19 patients who were sick in March and still can't smell?

Yes. It is now important to assess whether these are a few extreme exceptions. But if even one percent of millions of people with the disease permanently lose their sense of smell, that's obviously a lot of cases that need to be treated further.

Many report fluctuations: First the sense of smell and taste improved again, then they deteriorated again. Is that typical?

I find it rather surprising. However, I am not a medical doctor who specializes in this area. You also have to consider: If the smell fails, it leads to an enormous stress to observe oneself very closely. To objectify this a little, we have brought out the smell check, where everyone can smell things in their own household and evaluate this impression. We want to use it to give a regular stimulus to measure: How is it really changing? We already have more than 7,000 participants. That's where we're preparing the first analyses.

You mentioned that doctors can confirm with tests, "This person has a loss of smell." But I can tell that myself. Where is the added value?

Not every ENT doctor has these tests available. As a rule, you go to a specialized olfactory and taste clinic, such as the one in Dresden. Patients are presented with different concentrations of scents in a sequence they are not familiar with. This makes it possible to find out how sensitive the patient is. These tests are normalized, which means you have a lot of data about how this age, this gender should perform. And then you look at how much the patient deviates from that.

Can you also test for parosmia?

Yes, for example with an olfactory identification test: The patient is given a clearly smellable scent and has to say what it smells like. If he says something completely different, this is an indication that parosmia is present. It helps some patients to have a doctor tell them, "We have the test result, it behaves exactly as you say."

But what do you do then? Can one rely only on the time factor? On the fact that the cells will renew themselves again?

It is a terrible statement from a medical point of view. But "Be patient!" is a phrase that is used a lot. There is no miracle drug. But there are studies that suggest that smell training might help. Now we need to study whether that also helps with COVID-19-related olfactory disorders. So there's nothing more that can be done at this point except to give hope.

And to continue to do research?

Yes, more clinical trials are needed to look: What does it look like prospectively? The problem is: The clinics that care for the patients and test them must also have the interest to re-enroll them even later and examine them. And we will always lack the values from before the disease. It remains exciting. At least the great importance of smelling and tasting is now finally becoming clearer, which many doctors had dismissed as secondary compared to seeing and hearing.