A few times a week, Elizabeth Reninger ambles to a pizza restaurant near her job for lunch. She orders the same thing every time: a cheese slice and fries for $6. For a little adventure, she sprinkles on some Parmesan and red pepper flakes.

Before the coronavirus pandemic swept across the country, Ms. Reninger, a criminology student at Northern Arizona University who also works at a dog day-care facility, estimated that she ate pizza only once every couple of months. That changed late last summer when she strolled into a Slice and Ice pizza parlor.

“Maybe the warm, gooey cheese is some sort of comfort food for me with the pandemic,” Ms. Reninger said. “I go a couple of times a week, maybe three times some weeks, which is kind of embarrassing.”

For many Americans, pizza has been a perfect pandemic option, a comfort food for a time that is anything but comfortable. Whether a thin-crust version topped with fresh vegetables or a stuffed-crust pie piled high with sausage and pepperoni, pizza has checked many boxes during these strange times, primarily because it travels well and can easily feed — sometimes fairly inexpensively — an entire family. Over the first nine months of 2020, the combined revenue of Domino’s and Papa John’s grew so much that it was roughly equivalent to their selling about 30 million more large cheese pizzas than they had the year before.

In a year when restaurants across the country have struggled to stay afloat, with many unable to cover rent payments and pay employees because of government-mandated shutdowns, those that dished up pizza have generally fared better. Sales of pizza grew as much as 4 percent last year, according to Technomic, a food industry research and consulting firm. Pizza and chicken are the only foods categories expected to have grown.

“The pizza category as a whole was a big winner,” said Sara Senatore, an analyst who covers restaurants at Bernstein. Ms. Senatore noted that it may have become a go-to meal for families that found themselves on a tight budget because of falling wages or lost jobs.

For large pizza chains like Domino’s, Pizza Hut, Papa John’s and the privately held Little Caesars, the pandemic proved to be a sales boon. The four controlled 43 percent of the $44 billion U.S. market heading into the pandemic, according to Technomic. Some analysts say the big chains, most of which have not reported fourth-quarter earnings yet, almost assuredly gained more market share because their size allowed them to better navigate issues like paying rising prices for cheese and other ingredients, hiring additional help or covering rent after particularly lean weeks than independent pizza parlor owners.

For the first nine months of last year, combined revenues at Domino’s and Papa John’s increased almost 12 percent, or $434 million. Pizza Hut’s revenues for the same period were down a tad from 2019’s levels. The chain was in the midst of a turnaround plan when it had to deal with Covid-related closings and restrictions at its dine-in restaurants across the country. Even frozen pizza performed well during the pandemic, with sales climbing nearly 21 percent to more than $6 billion, according to NielsenIQ.

“Pizza was the perfect food for the pandemic, but I think it’s also the perfect food for all time,” said Ritch Allison, the chief executive of Domino’s, which saw double-digit increases in same-store sales in the United States, starting last spring. In the past year, Domino’s stock has soared 40 percent, to $385 a share. In the fall of 2008, it traded at a low of $3.

“We entered the pandemic in a fortunate position,” said Mr. Allison, noting that the company had a robust delivery service and had invested in its digital capability over the past decade.

Still, as demand soared during the pandemic, Domino’s rushed to hire 30,000 people; ramped up its production of the fresh dough that is sent to all of its locations; and faced occasional shortages of ingredients as meat producers shut down because of coronavirus outbreaks in their facilities. Television commercials, which normally take months to plan and shoot, were reshot in a matter of days so they could feature drivers wearing masks as they made deliveries.

Mr. Allison said his company had also become quite nimble in responding to pandemic customer behaviors. When it noticed cheeseburgers and tacos were also popular pandemic options, it quickly created two specialty pies: cheeseburger and chicken taco. Both become hot sellers, Mr. Allison said.

“My new favorite is the chicken taco, and I add extra jalapeños to give it some zip,” he added.

The pandemic has been devastating to the restaurant industry over all. Last year, more than 68,000 restaurants closed permanently, with buffets, French bistros, and soup and salad spots being among the hardest hit, according to Datassential. But 11,000 restaurants opened during the pandemic. Pizzerias led the way, with nearly 2,000 openings.

Justin Morse and his partners had hoped to be serving their version of escargots (served in little ramekins with saltine crackers) and steak frites to diners when they opened Brasserie Brixton, a cozy, 45-seat French bistro in Denver, in July. But they became increasingly nervous as dining restrictions in the city expanded in the late fall, and they found themselves unable to apply for government relief programs like the Paycheck Protection Program because they could not show a history of lost revenue.

Mr. Morse and his co-owners knew they had to focus on delivery. Realizing that items like French onion soup do not travel particularly well, they did an about-face. Over Thanksgiving weekend, they built and installed a wood-fired pizza oven.

“What industry is already set up for delivery and takeout? Pizza,” Mr. Morse said. “We said, ‘Let’s mimic an industry that people are already comfortable with in terms of delivery and takeout.’” While their restaurant, temporarily renamed (Le) Brix Pizza & Wine, offers a classic Margherita pizza, it also sells pizzas with French flair. One comes with white anchovies and thyme and another with potato, crème fraîche and rosemary.

“We’re not selling enough pizzas to cover all of the costs, but it’s better than the alternative,” said Mr. Morse, who delivers the bulk of the pizzas himself. He said the group hoped to return to French fare in a few months, but was considering continuing the pizza business at a different location.

Mr. Allison of Domino’s said he believed that demand for pizza would remain robust even after the pandemic ended.

“We’ve been given the opportunity to serve a lot of new customers during the pandemic who had never ordered from us or not ordered in a long time,” he said. “We hope we’ve done a great job to serve them and that they become loyal customers.”