They were so careful, for so long. They got COVID anyway.

WASHINGTON — Fareha Ahmed had been cautious since the beginning of the pandemic. She had eaten in restaurants only three times. She and her husband were vaccinated and boosted, and their 7-year-old got vaccinated in November as soon as he was eligible. In mid-December, Ahmed, 39, who lives in Washington, D.C., met a former colleague for an outdoor lunch. A few days later, the family attended an indoor gathering for the first time with other families, to bake Christmas cookies.

Then COVID caught up with her.

Two days after the lunch, the colleague tested positive for coronavirus. Ahmed took PCR and rapid tests — both negative — and then for good measure took another PCR test the day of the cookie party; the other participants told her to come over and not worry.

But three days after the party she started feeling ill, and the next day her PCR test came back positive.

"Like garbage," was how she felt when she saw the result, which came shortly before Christmas. "Like my stomach basically was in my throat … like I'd just ruined everybody's Christmas, including my own family's."

Across the nation and the world, people who thought they knew how to avoid COVID are getting a rude surprise. Safety precautions that had for so long felt talismanic ― get vaccinated, mask up, avoid large indoor gatherings — have in the past week or two collapsed under the weight of omicron, a much more highly transmissible variant than the ones before it.

Schools and colleges returned to virtual learning. Flights were canceled as airline staff caught the virus. Long-anticipated holiday plans fell apart as people — young and old, vaccinated and unvaccinated — tested positive right and left. Those with negative tests worried it was only a matter of time.

They are likely right, according to Robert Frenck, professor of pediatrics and director of the Vaccine Research Center at the Cincinnati Children's Hospital. "You know what? You're probably going to get COVID, but it's OK," he said.

Instead of thinking they lost the race against the virus, Frenck encouraged people to redefine their concept of winning. "It's not that you failed," he said. "You actually succeeded. You dodged the bullet … What are people trying to prevent? Are we trying to prevent the common cold? Nobody's going to do that. You've gotten your booster, you've done everything, and you still get COVID, but how sick did you get?"

For most infected people with vaccines, he said, "What they're having is a cold."

» READ MORE: The World Health Organization is worried about a ‘tsunami’ of omicron and delta COVID cases

People misunderstand what the vaccine is designed to do, Frenck said, adding that unvaccinated people are dying at a rate 20 times higher than people who are vaccinated and boosted. "Vaccines are going to stop people from being hospitalized and from ending up in the ICU and from dying," he said. "This is nature saying, it hasn't gone away now, and we need to go out and get vaccinated."

But even if people are not feeling very sick, it can be hard to come to terms with a positive result after all the time and effort spent keeping the virus at bay.

The pandemic's long and continuing arc has made it harder for people to process it, said Ilene Weingarten, a marriage and family therapist in Los Angeles who has seen patients sobbing over omicron, whether or not they've been exposed to it.

"It's the relentlessness of it," she said. "We're still absorbing the shock of March 2020, but we're still in it. The normal trajectory of a trauma that resolves is you go through it, you may repeat it over and over in your head, and that aspect fades after time and then ultimately it get metabolized into your system … But if it doesn't, it's trapped in your nervous system and you're reacting to it all the time."

The narrowing of people's lives over the past two years contributes to a more depressive outlook, Weingarten said. "You don't see the world in a wide way, you don't see context," she said. "It has an immense mental health toll, immense; with omicron in particular, there's been a spike in disheartened feelings, feelings of hopelessness and helplessness."

Adults 40 and under are having an especially difficult time, Weingarten said. "Everyone's disheartened, but I think it's hit millennials harder," she said, noting that that generation's adulthood has been marked by 9/11, the Great Recession and now COVID. "You already feel like you were sold a bill of goods, like, 'I did all the right things and now this.' There's a sense that there's no end to the misery."

Some who are now getting COVID feel resentful toward those who have resisted vaccines and other safety protocols.

» READ MORE: Worries that the omicron surge could lead to a breakdown in essential services spurred the CDC’s new isolation rules

Tatiana Laborde, 36, of Washington, said her family was careful to limit interactions during the pandemic. They raced to get the vaccine when it came out and got their children, now 8 and 6, vaccinated as soon as they were eligible.

But several days before Christmas, her older son tested positive, and after a few negative tests Laborde and her husband tested positive Sunday. She thinks her son picked it up at school, where there had been an exposure.

Her son and husband have experienced mild flu-like symptoms; Laborde felt more run-down and couldn't sleep for a couple of nights. She said the positive test results made her feel "defeated."

"I know we're going to be fine, I know we're not going to the hospital," she said. "It's just that thing where we've been so careful, and not everyone in the country takes it seriously, so there's that anger."

When Ahmed learned she was positive, she felt a surge of dread. She texted everyone else who had been at the cookie party — six adults and four kids — to let them know they had been exposed. "They said, 'Look, it's not your fault, don't blame yourself,' " she said. "But I said, 'If you test positive, it's my fault.' " Their tests all came back negative.

Ahmed's symptoms have been up and down: she has felt tired with a mild sore throat, chest pressure, and intermittent headaches and body aches. She has been sleeping in the basement, isolated from her husband and two children. All have been wearing masks around the house, and they canceled Christmas at her in-laws' in West Virginia. Their neighbors are in a similar situation. In this latest wave, it seems everyone knows someone who has tested positive.

The timing of omicron has felt especially cruel, spreading across the country just as boosters became widely available and families prepared for holiday gatherings. In fact, boosters had made some feel they could finally ease up on their precautions.

Jo McDaniel, 40, says she was "hypervigilant," testing weekly as she and her wife prepared to open a new bar near their house in Washington. As omicron ramped up, they started testing more often. Even after being fully vaccinated, they had barely gone anywhere without masks. But after receiving their boosters, they attended a few networking events and ate dinner out unmasked. "It felt a little bit freeing … that felt kind of awesome," McDaniel said.

A week before Christmas, her wife tested positive. She was mostly asymptomatic. But McDaniel said she felt duped.

"We were starting to sense some sense of normal, and then got lax, being around people we didn't know or who weren't in our pod," McDaniel said. "We felt this sense of security to safely do that … the sense of hope that the vaccine and booster was going to keep us safe. Now I feel like a real fool. I feel like we let our guard down prematurely because we wanted it to be over, we wanted to hug people."

» READ MORE: New COVID-19 cases in the U.S. soar to the highest level on record

That is understandable, Frenck of the Cincinnati Children's Hospital said, adding that people can only live with heightened awareness for so long. "Either they let their guard down or their systems go haywire," he said. "They can't tolerate it anymore, they're done. The world is done. We're interactive people, we're social creatures; we want to be around other people."

With vaccines and boosters, most people can follow that instinct despite omicron, he said. Vaccinated people who are upset about getting mild cases now are "operating on an emotional level rather than a rational level. The curves of hospitalization and deaths of people who have been vaccinated are basically flat."

Still, for many, getting the virus was a harsh reminder that life is still not back to normal.

McDaniel and her wife canceled their plans to go home to Ohio for the holidays.

“I think we’ll go back to vigilance in terms of going out as little as possible … ordering takeout,” she said.

Ahmed and her husband and kids had a quiet holiday at home.

“At first I was like, ‘I ruined Christmas,’ " she said. “But then I was like, ‘No, we’re going to have a different Christmas this year.’ "