On the first day of spring, Grace Lawlor woke up, brushed her teeth and realized she couldn’t taste her toothpaste. Then she took a shower, and realized she couldn’t smell her shampoo. It struck her as odd, but nothing to be too worried about; she felt otherwise fine.

“My roommate and I were almost laughing about it,” says Lawlor, 25, who lives in Boston. “Like, what the heck is this? It was the craziest thing.”

The roommate didn’t believe her, so she decided to prove it by putting hot sauce on her tongue.

“It was as if I was drinking milk,” she says. “I could literally bite into an onion like it was an apple. And there was just nothing there. It was just absolutely bizarre.”

In a consultation with Dr. Google, she learned that a sudden loss of taste and smell can be a sign of the novel coronavirus. She went to a doctor, but was told she couldn’t be tested because, at the time, that clinic was only testing essential workers. Her doctor told her to assume she was positive for covid-19, so she went home to quarantine. A few days later, one of her roommates was stricken with the same symptoms.

They settled in for a joyless 10 days of putting food in their mouths and then swallowing it — “eating” would be the wrong word for it, because eating is a pleasure. This was mechanical. Lawlor bothered with it less and less.

“There was no point,” she says. “Even if I had a craving for something and I had that item right in front of me, there was no satisfying it because we couldn’t taste it.”

A similarly disorienting scenario was happening elsewhere in Boston, where Jenny Dwork had come from New York to her mother’s house to work remotely for her job overseeing e-commerce for a shoe company. Dwork felt a little under the weather on March 24 — tired, some mild cold symptoms — but was otherwise fine. Until she made herself a shake and realized she could feel “the sensation of the cold, but couldn’t actually taste the ingredients.” Knowing it might be a sign of covid-19, she went to a drive-through testing center, but was turned away because she had no other symptoms.

Friends encouraged Dwork to try some other strong flavors, like sriracha, and later, at a virtual happy hour, the dares escalated.

“I’m staying at my mom’s,” she explains, “and there’s just like, 30 years’ worth of weird alcohol here in her pantry.” Dwork had a shot of raspberry vodka “that was probably from my high school days.” Then some Southern Comfort. She felt the alcohol burn on her throat but tasted nothing. The next day Dwork felt symptoms indicating another ailment: She had a hangover.

For a pandemic illness that can be ghastly and unpredictable, the weirdest symptom is quite common. A study of European covid-19 patients found that 85.6 percent and 88 percent of patients “reported olfactory and gustatory dysfunctions, respectively.” In an Iranian study, 76 percent of covid-19 patients who reported a loss of smell said it had a sudden onset — as if scent could be switched on and off, like a lightbulb.

The technical term for a loss of smell sense is anosmia. Congestion is the most common culprit, but some viruses can interfere with our olfactory processing. With covid-19, researchers are still trying to understand exactly how it happens. Some think that the virus can target the nervous system through the olfactory bulb, the nerves in our nose that help us smell. They’re also paying attention to the olfactory epithelium, the skin surrounding those neurons, which have cells similar to the ones the virus targets in the lungs.

Because neurons regenerate, in “roughly seven days, most people have had some start to recovery,” says James Denneny, executive vice president and CEO of the American Academy of Otolaryngology–Head and Neck Surgery. Researchers say long-term loss is possible, but rare.

The short-term implications are more urgent: Loss of smell or taste could be an indication that someone may be a virus carrier even if they don’t have a cough, fever or other typical symptoms. Rep. Joe Cunningham (D-S.C.) reported that he tested positive for covid-19 with only smell- and taste-related symptoms. Rudy Gober, the Utah Jazz player who was the first in the NBA to test positive, says he lost his senses, too. Other celebrities, including former “Bachelor” star Colton Underwood, “Lost” actor Daniel Dae Kim and Broadway star Aaron Tveit have reported similar symptoms. One quarter of people who reported the symptom said it was the only one they experienced.

Which puts the Smell and Taste Victims in the deeply strange position of watching the news in horror, hearing tales of patients dying in hospitals and knowing the same virus was in them, too — with effects that are somehow far milder, yet freaky.

“It scared the hell out of me,” says Vallery Lomas, a 34-year-old champion baker, who feared she would never get her senses back. “I could smell nothing for probably five days.”

That’s an occupational hazard for Lomas, because she was presumed positive for covid-19 in the midst of writing a cookbook. Smell and taste are closely related, and culinary professionals rely on their senses to fine-tune recipes. Lomas had to ask her publisher for an extension, and, instead of smelling the warm hug of a freshly baked cake, she spent a week sniffing a bottle of gross-smelling cough syrup, hoping a whiff would return.

Her sense of smell is back, but it’s not 100 percent. “I started to freak out this morning,” she says, when she was testing a recipe and noticed a lack of detail in her perception. “Even though I could taste those flavors, I still can’t really smell and really taste to the level of knowing, is this too sweet? Does this need more cinnamon? Is this other flavor overpowering? Is it balanced? I have no idea.”

Because smell and taste are intertwined, some people who think they have lost both senses may have only lost their sense of smell. “What happens with loss of the sense of smell is you lose flavor,” but not taste, says Jo Shapiro, associate professor of otolaryngology at Harvard Medical School. (Yep, there’s a difference: Taste is the basic modalities of sweet, salty, sour, bitter and umami, but flavor is more precise. Plug your nose and try a strawberry and a cherry gummy bear: You’ll be able to tell that both are sweet, but you won’t be able to distinguish between the flavors.)

Shapiro knows from personal experience. She was presumed to have contracted covid-19 — she was denied a test because it was early in the pandemic and she had not been abroad — when she traveled to a conference. She experienced the full range of symptoms (fever, chills, fatigue, cough) and realized one morning, after her husband made her breakfast, that she could no longer smell anything.

“I said, ‘I hate to criticize your cooking, but I feel like you’ve dumped an entire container of salt on these eggs,’ ” Shapiro says. He hadn’t: The salt her husband had put on the eggs was the only component of the dish she could taste. The lightbulb went on: “I was like, oh, my God, I have lost my sense of smell.” Given Shapiro’s specialty, “It was kind of ironic,” she says. She’s still waiting for it to come back.

Other patients can also lose their sense of taste entirely, like onion-eater Lawlor, who could taste nothing at all. Thomas Finger is a professor of cellular and structural biology specializing in taste at the University of Colorado Anschutz Medical Campus. Based on accounts he’s collected from around the world, “The very peculiar thing about the covid taste loss is that it may preferentially affect sweet,” he says, meaning for some people, that’s the first taste to go — but it remains unknown why tastes would not be impacted equally.

The research continues — not just in the medical community, but in households where likely covid-19 sufferers, blessed with cases that do not require hospitalization, have been conducting their own experiments.

“I read somewhere that honey and cinnamon was something to try,” says Mandy Hardy, 42, who lives in Brooklyn and lost both of her senses last week. “I’m putting that in my tea and it’s not working. Nothing’s working,” she says. Every day, she takes a deep hit from her Vicks VapoInhaler in the hope that it will jump-start her nose. (She now says her smell sense is about 50 percent back-to-normal.)

Sue Kinnamon, a professor of otolaryngology also at Colorado-Anschutz, says people who are afflicted can try “smell training” — exposing themselves to strong scents like mustard, something they are probably doing anyway — though she cautions there is no evidence that it is effective in bringing back a covid-based loss of smell.

Kevin Knocke, 33, recently took up cooking as a hobby. When the pandemic struck, he stocked his Manhattan pantry with choice ingredients in anticipation of a long shelter-in-place. He imagined comforting himself with homemade pizza and takeout meals from his favorite New York restaurants. “I was so looking forward to it,” he says. “It was going to be so much fun.”

Then he lost his senses of smell and taste. He felt okay otherwise. And the anosmia actually had its advantages.

“I ended up cleaning all my kid’s poop for the next two weeks and changing diapers,” he says. “I was an inch away from it, could not smell a thing. And this kid can produce a stench.”

Those who lose their sense of smell or taste need not resign themselves to a lifetime of joyless eating. The AAO-HNS found that the average length of time patients experience those symptoms was seven days, with 85 percent of patients regaining their senses within 10 days.

When that first whiff returns — and with it, some semblance of flavor — it’s off to the pantry for a true bacchanal of all the foods that anosmic sufferers had been missing.

“I just kept thinking, I’m really going to appreciate every single thing that I eat and not just shovel stuff into my face,” says Dwork, who began to regain her senses with a cup of morning coffee. Hardy longs for pizza. Knocke delayed his birthday celebration until he could taste takeout once more.

As for Lomas, she’s putting the finishing touches on her cookbook, tentatively titled “Life is What You Bake It.”

“It’s about making the best out of tough circumstances,” she says, and she’s had a few more of those in the past month. Some of the intro texts for her recipes “now include discussion of pandemic survival.”