Another reason not to pick your nose, besides it being rather unseemly and possibly linked to dementia, is that it may increase your risk of catching COVID-19, according to a newly published study.

Researchers from the Vrije Universiteit Amsterdam in the Netherlands wanted to look at healthcare workers at greater risk of picking up the SARS-CoV-2 virus – and how factors such as picking your nose or wearing glasses might affect that risk.

A total of 219 health professionals completed the study survey, and those who admitted picking their noses were more likely to get COVID-19 over the course of six months: the infection rate was 17 percent for habitual nose pickers compared to 5.9 percent for the others.

This doesn't prove that nose picking caused the infection; it only highlights an association. However, the researchers think that the nose-picking act might transfer unhealthy bugs to the mucosa (or soft membrane) inside the nose.

"It can be hypothesized that regular nose picking and nail biting in an environment with high levels of circulating virus enables the virus's transfer to the nasal or oral mucosa," write the researchers in their published paper.

No significant differences in infection rates were associated with wearing glasses, having a beard, or regularly biting nails (though the researchers suggest that biting nails probably isn't a good idea anyway).

We're probably looking at the virus traveling in both directions here; it's known that there's a high nasal viral load for SARS-CoV-2 right after the infection happens and before symptoms appear, which can then be transferred to shared work surfaces by nose picking.

The habit could then also be responsible for someone else picking up the virus from surfaces and transferring it to the nose, where it then infects. The researchers aren't certain that this is what's happening, but it seems likely.

We don't have any definitive scientific evidence for why people pick their noses, but we do know that it can affect the microbiome of the nasal cavities and that it's not only humans that have picked up the habit.

While this study is only based on self-reporting and would need more controlled experiments to back it up, it does broaden our thinking about how COVID-19 can be contracted, especially in healthcare settings.

SARS-CoV-2 infections haven't gone away, and for many people, symptoms can stick around for several months or more, so scientists are still keen to study how COVID-19 spreads.

"Nose picking has not been reported before as a risk factor for contracting SARS-CoV-2," write the researchers. "Our findings highlight the importance of the nasal cavity as a main transit port for SARS-CoV-2."

The research has been published in PLOS ONE.