Why smell checks might work better than fever checks for COVID-19 screening

We’ve all been through the “non-contact infrared thermometers” businesses use to check if you have a fever, and possibly COVID-19. Heck, my hospital and gym do it every time I come in.

The problem is that they don’t work very well. You could have COVID-19 without a fever, and pass the test. Or you could have a fever that isn’t caused by COVID-19.

Here’s another idea: smell tests.

Loss of smell, or anosmia, is an earlier symptom of COVID-19 than fever. The cells that line your nasal cavity are infected by the coronavirus early in the disease process, before your body has mounted an immune response that causes fever.

And unlike temperature checks, which might detect a fever caused by an infection other than COVID-19, a recent Mayo Clinic study found that COVID-19 patients were 27 times more likely than others to have lost their sense of smell.

The smell test could be as simple asking people to identify a particular scent from a scratch-and-sniff card.

Many people infected with COVID-19 don’t realize they have lost their sense of smell. But studies have shown scratch-and sniff tests can identify nearly 80% of COVID-19 patients who have lost their sense of smell.

And to catch people who might cheat, businesses could use smell tests that ask people to smell a scratch-and-sniff card and pick the correct odor out of four choices. Or the card could have three areas with different intensities of odor. One could be a blank, to identify people who falsely claim they can smell.

With high numbers of cases in much of the country, smell tests could soon help us identify people who could spread COVID-19.