Checks are a Flawed Way to Flag Covid-19 Cases. Experts Say Smell Tests Might Help

Fever Checks are a Flawed Way to Flag Covid-19 Cases. Experts Say Smell Tests Might Help

Unfortunately, temperature checks could well join the long list of fumbled responses to the pandemic, from the testing debacle to federal officials’ about-face on masks.
Workplaces do it. Newly reopened public libraries do it. LAX does it. Some restaurants, bars, and retail stores started doing it when governors let them serve customers again: Use temperature checks — almost always with “non-contact infrared thermometers” — to identify people who might have, and therefore spread, the infectious disease.

Unfortunately, temperature checks could well join the long list of fumbled responses to the pandemic, from the testing debacle to federal officials’ about-face on masks.

Because many contagious people have no symptoms, using temperature checks to catch them is like trying to catch tennis balls in a soccer net: way too many can get through. On Tuesday, the head of the Transportation Security Administration told reporters, “I know in talking to our medical professionals and talking to the Centers for Disease Control … that temperature checks are not a guarantee that passengers who don’t have an elevated temperature also don’t have Covid-19.” The reverse is also true: Feverish travelers might not have Covid-19.

In this case, however, a growing body of science suggests a simple fix: make smell tests another part of routine screenings.

Of all the nose-to-toes symptoms of Covid-19, the loss of the sense of smell — also known as anosmia — could work particularly well as an add-on to temperature checks, significantly increasing the proportion of infected people identified by screening in airports, workplaces, and other public places.

“My impression is that anosmia is an earlier symptom of Covid-19 relative to fever, and some infected people can have anosmia and nothing else,” said physician Andrew Badley, who heads a virus lab at the Mayo Clinic. “So it’s potentially a more sensitive screen for asymptomatic patients.”

In a recent study, Badley and colleagues found that Covid-19 patients were 27 times more likely than others to have lost their sense of smell. But they were only 2.6 times more likely to have fever or chills, suggesting that anosmia produces a clearer signal and may therefore be a better Covid-catching net than fever.

There is no definitive study on the predictive value of temperature checks for Covid-19. But there are clues from when that strategy was used during the SARS epidemic of 2003. Deployed at airports, especially in Asia, the devices fell far short of the ideal, an analysis found. Although contact-less thermometers are quite accurate if used correctly, many other conditions (including medications and inflammatory disease) can cause fever. As a result, the likelihood that someone with a fever had SARS ranged from 4% to 65%, depending on the underlying prevalence of the disease.

The likelihood that someone with a normal temperature reading was SARS-free was at least 86%. That suggests SARS fever checks didn’t miss many infected people. Unlike SARS, unfortunately, Covid-19 can be contagious even before an infected person runs a fever, which makes missed cases more likely.

As experts have cast around for other screening tools, some have zeroed in on smell tests, which could be as simple asking people to identify a particular scent from a scratch-and-sniff card. Though not a universal symptom, loss of smell is one of the earliest signs of Covid-19 because of how the virus acts. Support cells in the olfactory epithelium, the tissue that lines the nasal cavities, are covered with the receptors that SARS-CoV-2 uses to enter cells. They become infected very early in the disease process, often before the body has mounted the immune response that causes fever.

“These support cells either secrete molecules that shut down the olfactory receptor neurons, or stop working and starve the neurons, or somehow fail to support the neurons,” said Danielle Reed, associate director of Monell Chemical Senses Center, a world leader in the science of taste and smell. As a result, “the [olfactory neurons] either stop working or die.”

In an analysis of 24 individual studies, with data from 8,438 test-confirmed Covid-19 patients from 13 countries, 41% reported that they had lost their sense of smell partly or completely, researchers reported in Mayo Clinic Proceedings. But in studies that used objective measurements of smell rather than simply asking patients, the incidence of anosmia was 2.3 times higher.

A Monell analysis of 47 studies finds that nearly 80% of Covid-19 patients have lost their sense of smell as determined by scratch-and sniff tests, Reed said. But only about 50% include that in self-reported symptoms. In other words, people don’t realize they have partly or even completely lost their sense of smell. That may be because they’re suffering other, more serious symptoms and so don’t notice this one, or because smell isn’t something they focus on.

UC San Diego Health is doing that. It asks about loss of smell (and taste) when it screens visitors and staff before allowing them to enter its buildings.

Because many people are unaware of their anosmia, testing would be even better than asking, Reed said.

The gold-standard test is the University of Pennsylvania Smell Identification Test, called UPSIT. It uses 40 microencapsulated scents — including dill pickle, turpentine, banana, soap, licorice, and cedar — released by scratching with a pencil. The test taker has a choice of four answers for each, and the whole thing takes 10 to 15 minutes.

A screening test for anosmia in the context of Covid-19 could be much simpler, experts say, especially since the idea is to identify whether individuals can smell or not, rather than whether they can discriminate different scents.

“I can see several practical ways is to have people check their sense of smell as a routine matter when entering public areas,” Reed said. Medical offices could “ask people to smell a scratch-and-sniff card and pick the correct odor out of four choices. For workplaces and schools, one way is to ask people to ‘stop and smell the roses’ as they enter buildings and report abrupt reductions in their ratings of odor intensity.”

To avoid cultural bias (not everyone knows what bubblegum or grass smells like), a test for anosmia in Covid-19 could have a standard amount of phenyl-ethyl alcohol (which smells like roses) on a swab or stick and have people sniff it, Reed said. A second stick could have less, testing for diminished sense of smell. A third stick could be a blank, to identify people who falsely claim they can smell.

Contributor: Sharon Begley, Senior Science Writer – STAT News

Dietitian-Approved Superfoods for Summer Salads

Dietitian-Approved Superfoods for Summer Salads

Include these ingredients to create salads packed with nutrition and deliciousness.
SUMMER MAY BE IN FULL swing – with picnics and BBQs – but keeping our immune systems healthy remains at the top of everyone’s mind right now. Why not take advantage of the season’s bounty of fresh veggies and fruits and feed ourselves things that boost our immune system?

Food doesn’t kill viruses, but certain foods can strengthen our immune systems and help fight off unwanted illness. Oftentimes, illness and immunity are thought of more frequently in the wintertime, and foods like stews and soups are our go-to items. But these superfoods pair perfectly in summery salads.

Ginger and Garlic
Aromatic and loaded with flavor, both garlic and ginger contain compounds that naturally support your immune system. Coming from the allium family, garlic contains compounds that naturally aid in the destruction of bacteria and infection. There’s research that shows eating garlic helps to reduce the risk of becoming sick.

Garlic helps flush the body of harmful toxins, stimulating immune responses and reducing bodily inflammation. Add a few minced garlic cloves to a salad like Memphis-based dietitian Sylvia White at does with her quinoa salad with tomatoes, cucumber and mint.

Ginger is another ingredient many turn to for illness prevention. Ginger may help decrease inflammation, which can help alleviate a sore throat. Ginger may speed up digestion, and it’s packed with vitamins, says dietitian Shena Jaramillo, founder of in Ellensburg, Washington. She makes a salad dressing with fresh ginger and garlic. She mixes mango, tahini, ginger, garlic, olive oil and balsamic vinegar in a blender – ready to toss on your favorite salad.

Many people turn straight to vitamin C after they’ve caught a cold. That’s because it’s known to help build up your immune system. Vitamin C is thought to increase the production of white blood cells, which are key to fighting infections.

Almost all citrus fruits are high in vitamin C. With such a variety to choose from, it’s easy to add a squeeze of this vitamin to any meal. Popular citrus fruits include grapefruit, lemons, limes, oranges and tangerines. These fruits tend to go very well in summer salads or in a homemade dressing. Nashville-based dietitian Karman Meyer, founder of, likes to pair fresh-squeezed pink grapefruit, orange and lime juice in a citrus vinaigrette with salmon – rich in omega-3s – and greens.

Because your body doesn’t produce or store vitamin C, you need to ingest it daily for continued health. The recommended daily amount for most adults is around 75 mg for women and 90 mg for men.

Dark leafy greens in general are great for our immune systems due to the myriad of nutrients they contain. Spinach specifically makes my list because not only is it rich in vitamin C, it’s also packed with numerous antioxidants and beta carotene, which may increase the infection-fighting ability of our immune systems.

Spinach is healthiest when it’s cooked as little as possible so that it retains its nutrients. However, some light cooking makes it easier to absorb the vitamin A and allows other nutrients to be released from oxalic acid, which is an organic compound found in a variety of plants.

Wisconsin-based dietitian, chef and cookbook author Julie Andrews created a salad recipe on her website, The GourmetRD, full of immune boosting ingredients: fresh baby spinach, strawberries, fennel, avocado, snap peas and almonds.

Sunflower and Pumpkin Seeds
Sunflower and pumpkin seeds are full of immune boosting nutrients. Sunflower seeds contain phosphorous, magnesium and vitamins B-6 and E. Vitamin E is important in regulating and maintaining immune system function.

Sunflower seeds are also incredibly high in selenium. Just 1 ounce contains nearly half the selenium that the average adult needs daily. There have been a variety of studies looking at selenium’s potential to combat viral infections, but they have mostly been performed on animals.

Pumpkin seeds contain zinc and iron, which are both vital for immune function and possess anti-fungal and anti-viral properties. They are also not a common trigger of allergies and intolerances. And both can be easily sprinkled on just about any salad.

Dietitian Melissa Groves Azzaro uses them in her festive salad that also includes pomegranates and honey – two more superfoods – along with green apples, greens and an orange-lemon juice dressing. Based in Portsmouth, New Hampshire, she’s the owner of Avocado Grove Nutrition & Wellness.

Red Bell Peppers
While citrus fruits have lots of vitamin C, check out the vitamin C content of a red bell pepper: One medium sized bell pepper contains 152 milligrams of vitamin C, which fulfills your recommended daily allowance. They are also a rich source of beta carotene, which our bodies convert into vitamin A, which is important for healthy skin, eye sight and immune system. Bell peppers are excellent chopped up in a salad. Colorado- and Minnesota-based dietitians Stacie Hassing and Jessica Beacom, known as the Real Food Dietitians at, created a salad chock full of red bell peppers, kale, mango and avocado, plus chicken for added protein. I love the variety of nutritious vegetables this recipe contains.

Contributor: Carrie