America this week began to consider the existential threat of a doorknob. The horror of a touch screen in the self-checkout lane. The inescapable doom that accompanies any trip on public transportation. The realization of how much, exactly, we all touch our faces each day: constantly.

Last week, you pressed elevator buttons with abandon. You weren’t afraid of the free weights in the gym. You washed your hands for barely enough time to say “Happy Birthday” once, let alone sing it twice.

How bold are you now?

Covid-19, the disease caused by novel coronavirus that originated in China and recently arrived in the United States, has already transformed our personal worlds. A subway pole is now a memento mori. An itchy eye is a trap. A cough is a harbinger.

And in New York City, which acknowledged its first case of covid-19 on Sunday (and has since confirmed several more), everyone is coughing. At least, that’s how it seems to Ezra Butler. The 38-year-old consultant the other night found himself surrounded by sneezing people in a Broadway theater. He sees people coughing on the street and sniffling on the subway.

“I will hold my breath, and the second we get to the station I’ll go and switch cars,” he says.

Symptom of coronavirus: shortness of breath.

Symptom of coronavirus anxiety: holding of breath.

Butler has seen unexpected breathing disruptions, too, though not because of any virus. He says that thinking about all the possible ways he could catch coronavirus while out and about has given him several “micro panic attacks.” “I can’t think. I’m freezing up. I can’t focus. My breathing changes,” he says. “And my whole body is basically telling me, ‘Get out.’ “

As if there weren’t enough to be anxious about.

“This may be, for some individuals, the stressor that tips them over the edge,” said Lynn Bufka, a clinical psychologist and the senior director of practice, research and policy for the American Psychological Association. “To the public, it’s very new. We don’t know a lot about it. Information about it keeps changing. . . . That’s what causes us stress: things that are novel but uncertain.”

Coronavirus anxiety has outpaced the virus itself. Convenience-store shelves have been raided of hand sanitizer. Ditto surgical masks. Health officials have chided panicked Americans who are buying up the masks, saying that they aren’t useful if you’re not already sick and that hoarding them may keep them out of the hands of those who need them. (“Seriously people — STOP BUYING MASKS!” tweeted the U.S. surgeon general on Saturday.)

Symptom of coronavirus: cough.

Symptom of coronavirus anxiety: panic-shopping.

“Everything feels disgusting to me now,” says Pandora Orr, 36.

Orr lives in Chicago, which has yet to see a rash of confirmed cases. If she sets her lunch bag on the counter at work, she has to clean the bottom of it. She’s wiping down her laptop whenever she has to take it to another room for meetings.

“As I’m talking to you in this conference room, my elbows are on this desk,” she said, just now considering that they, too, would need to be Purelled. “I feel like I’m going a little crazy.”

It was in the middle of a trip to London, Brussels and Paris last week that Erin Fogerty, 23, realized that coming home to Seattle would be no safer than being abroad. Washington state has the most confirmed cases in the country, with at least 28 confirmed patients and nine deaths. (In general, the World Health Organization says that about 3.4% of people diagnosed with the disease covid-19 have died.)

“If I don’t think about it I’m fine, but when you start thinking about these gross crazy germs” it can quickly spiral into obsession, she says. “Touching doorknobs and elevators, that type of thing is becoming very scary to me.”

Symptom of coronavirus: fever.

Symptom of coronavirus anxiety: disorienting awareness that every surface is crawling with microorganisms.

Nikhil Merchant, 38, has taken to meticulously wiping down the treadmill at his suburban Los Angeles gym before he uses it. “Your senses are heightened to kind of superimpose germs sitting on that machine,” he says.

Merchant had completed the ritual on Monday and was about to begin his run when he spotted a wad of chewing gum in the treadmill’s cellphone pocket and fled the gym in overwhelming disgust.

“I had to rethink, why am I being so paranoid?” he says.

Suspicion of treadmills and elevators mutates into suspicion of fellow humans: Are other people washing their hands for two “Happy Birthdays”? How much do I really know about the habits and histories all these friends and co-workers and strangers who are touching all the things I’m touching right before I forget not to touch my face?

At a Boston cooking class last week, Rodrigo Martinez, 47, realized that the whole class would be touching the ravioli dough during the lesson, and he couldn’t help but wonder whether any of his fellow students had recently spent time in China. On Long Island, New York, 74-year-old Randy Foss canceled her weekly mah-jongg group after she thought a little too long about how everyone has to touch the tiles that are used to play the game.

Melanie Dahlberg, 62, who lives in Renton, Washington, a half-hour drive from the coronavirus hotspot of Kirkland, was unable to convince her adult son and daughter that she did not have disease after coming down with a nasty bout of nausea and a fever on Sunday.

“I said, ‘I’m fine. This is just like the flu I’ve had my whole life. Let me suffer in misery,’ ” Dahlberg says.

She drove to urgent care and waited two hours by herself before a doctor sent her home with a note to reassure her kids: She had a regular flu.

In San Antonio, the archdiocese issued a recommendation that churches remove fonts of holy water from church entrances; many Catholics dip their fingers into the water to mark themselves with the sign of the cross.

On a Royal Caribbean “Star Trek”-themed cruise that departed Miami on Sunday, signs onboard suggested “Vulcan salutes or elbow bumps only.”

Anna Vagnerini, a 30-year-old marketer in Charlotte, North Carolina, went to Whole Foods the other day to pick up some fancy sparkling water and coconut shrimp, but when she saw the picked-over shelves of canned goods she decided to get some frozen broccoli, bell peppers and cannellini beans, too.

The vibe in Charlotte reminded Vagnerini of the calm days leading up to a hurricane — the jarring dissonance between the sunny weather outside and the electrical current of low-grade panic that crackles through the air — “it’s this small impending dread, because you don’t know what’s going to go wrong, and it’s all that anyone ever talks about.” (One case has been reported in Raleigh, a 2 1/2-hour drive away.)

The impending dread isn’t small for people who are a generation or two older, who may be more vulnerable to covid-19, says Jameca Falconer, a St. Louis psychologist.

In Huntsville, Alabama — a state roiled by rumors of a government plan to quarantine coronavirus patients there — Lauren Brown opened Facebook on Monday to see her grandmother, who is in her 70s, had shared someone’s post advising people to ward off the virus by putting Neosporin up their nose with a Q-Tip.

“DO NOT DO THIS,” Brown immediately texted her grandmother, who eventually backed off from the idea. (Setting aside the nose thing, the Centers for Disease Control and Prevention does not list Neosporin as a coronavirus treatment.)

Min Pummalee, a 26-year-old graduate student in the District of Columbia, has told her parents not to fly from Thailand to attend her May graduation ceremony, because their flight was booked on Korean Air, and she’s worried they’ll get sick or be quarantined, which would be tough for her prediabetic father to handle.

In the meantime, Pummalee is desperately trying to stop touching her face. She knows that surgical masks don’t help, but she’s taken to wearing one on the train anyway, she says, because “if I touch the mask instead of my own face, it will be better.”

She doesn’t trust the people around her to wash their hands.

She doesn’t trust herself.

She doesn’t even trust the chemicals in her hand sanitizer.

“I know it’s like 99.9%” effective, she said. “But I think, what’s going on with that 0.1%?”

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