The Nose, the Lungs, and in Between

A Raleigh News & Observer story reprinted in today's Pioneer Press led me to this report from the University of North Carolina at Chapel Hill. It tells of research newly published in the journal Cell, which finds the coronavirus takes root in our nasal cavities best, more than through our mouths or even our lungs. From there, when it attacks the lungs in its most unfortunate victims, it's because they have aspirated mucus from their nasal passages, rather than that they had directly inhaled the virus as an aerosol or droplets into their lungs from the air.

This has a couple of implications: wearing a mask to protect your nose, particularly, becomes even more important. The possibility of preemptive treatments, such as nasal flushes or sprays come to mind immediately.

As support for the aspiration hypothesis, the researchers offered this:

...the researchers mapped the sites of coronavirus infection in the lungs of several people who had died from COVID-19 and found that these sites exhibited a sort of patchiness and other characteristics consistent with the hypothesis that these sites had originated from infection higher in the airway.

The theory that aspiration of oral contents into the lung is a significant contributor to COVID-19 pneumonia is consistent with observations that people at higher risk for severe lung disease — the elderly, obese and diabetic — are generally more prone to aspiration, especially at night.

So if they are correct, these "underlying conditions" are not directly interacting with the disease to cause complications and death, but they create a condition that allows the virus to get somewhere it otherwise wouldn't reach, and in younger and healthier people generally doesn't reach.

In the News & Observer story, one of the researchers was quoted this way:

If [the people who died] got the coronavirus directly from breathing it in the air, it would be evenly spread out in the lungs. “You would expect the lung to look like it had one big veil of COVID-19 coming down over it,” Boucher said.

Instead, spots of severe infection were next to healthy tissue. This supports the theory that the lungs are infected when mucus and other liquids are aspirated into the lungs.

“If you get a teaspoon down the wrong way, it’s going to go preferentially down a few airways,” Boucher said.

Most of the infected patches were in the lower lungs, another sign of a falling liquid. These findings matched with X-ray observations of COVID-19 patients showing more diseased patches lower in the lungs.

If this aspiration hypothesis turns out to be true (and it seems fairly well-grounded to me), I have to say I'm a bit freaked out by this, since I think of myself as having kind of a lazy epiglottis. I'm not sure if that's true or not, but it seems as though I choke on beverages or my own saliva more than average. Great.

I hope these researchers' general findings about the nasal passages lead to some effective treatments.