Yardley Wong, captive on the Japanese cruise ship grappling with the coronavirus, captured in a single image the essence of life under quarantine. From inside her tiny cabin, Ms. Wong took a picture of the closed doorway. She posted it to Twitter last week.

“So much wondering through this door,” she wrote.

From the Black Plague to the flu pandemic of 1918 to more recent outbreaks, the history of quarantine and medical isolation shows common emotional threads of those on both sides of such doors — uncertainty, terror, loneliness, separation. But this time, the raw physical barrier is showing cracks, thanks to the smartphone.

“After some emotional breakdown, I find my peace from you all,” Ms. Wong tweeted several days after her post brought messages of support from people around the world. “Thank you for the kindness. Your tweets give me strength.”

While newspapers, radio and television have softened the ordeal of past sequestrations, the coronavirus quarantines of 2020 are unlike any other in human history owing to almost universal digital connection.

Laptops, tablets and smartphones are allowing people in quarantine to work at their jobs remotely, order food, shop on Amazon, chat face-to-face with friends and loved ones, keep up with social media feeds, download movies and music — in short, to stay engaged in the world and fulfill many activities of their regular lives.

Karey Maniscalco, an American real estate agent who was quarantined with her husband, Roger, on the same cruise ship, found isolation surprisingly busy. “The last couple of days, we’ve been just catching up on work online, and doing a lot of Facebooking,” she said in an interview last week, before the U.S. government evacuated most American passengers from the ship and flew them back to the United States, where they will continue to be quarantined. “Our inboxes are constantly full. Keeping up on social media is surprisingly very time consuming.” She started posting TikTok videos to stave off what she said could be “overwhelming” emotion. “I woke up realizing that I’m still here and just started crying.” Engaging on social media, she said, “keeps me too busy to sit and dwell, I guess.”

In China, Isabel Dahm, 22, has been able to see her cats and dog back home in Minnesota through chats with her father, Bob Dahm, using an app, WeChat. She is in Zhejiang province, where she’s been teaching English since November and is now largely relegated to her apartment under semi-quarantine.

“I think if this was happening in the Middle Ages, I would’ve actually gone insane weeks ago,” Ms. Dahm said by email.

She is allowed out of her apartment only every other day, so she is teaching her class online from her computer in her small efficiency apartment. “I have a VPN, a virtual private network, so I’m able to access all of the things I could back in the States, like Netflix, Hulu and YouTube that are normally blocked in China,” she said. She also orders food delivery but the delivery people are not allowed upstairs.

“She’s learned the phrase in Chinese for ‘I’ll meet you at the gate,’” her father said.

More substantively, those under quarantine have had unprecedented access to information about the virus itself. For example, in Shenzhen, in the Guangdong province, which has the highest infection rate outside of Wuhan, Krista Lang Blackwood, a teacher from Kansas City, follows virus updates from the World Health Organization and the Centers for Disease Control and Prevention. Sometimes, she and her family look out their fifth-floor window and wonder if the quiet streets are telling them infection is spreading. Then they check the phone to find out.

In earlier times, Ms. Lang Blackwood noted in an email, people probably would have fretted over how close the nearest case of illness was. “In the 21st century, don’t worry! There’s an app for that!” she wrote.

“You can literally look at your neighborhood and see where each reported case is on a map. We have no idea who runs that app, since it’s all in Chinese, but, on the app, there is no red exclamation point at the apartment complex down the street.”

“It’s an odd combination,” she added, “of glut of information combined with isolation.”

This widespread connectivity appears to be changing the nature of isolation according to experts in two disparate fields — those who study the sociology of technology use and those who study quarantine. In 1918, during the flu pandemic, parts of the United States embraced a strategy called “social distancing” that was explicitly intended to limit interpersonal exposure. Only one-third of households had phones and people were afraid to touch newspapers, fearing the spread of germs.

Research, going back decades, shows specific instances in which new media helped limit isolation. Journal articles from the early days of radio show how radio transmissions lifted the spirits of people in isolation at hospitals. An experiment in the late 1950s in Omaha found that a closed-circuit television signal helped the mood of patients at a mental hospital when they could see and respond to their relatives.

In 1832, when a cholera outbreak struck North America, newspapers carried news of the infection as it spread.

“There is a long history of new media in transforming these moments over time,” said Dr. Jeremy Green, director of the history of medicine department at Johns Hopkins School of Medicine. The current media seems to combine all that which has come before — letter writing, video, radio and television, and all instantly and everywhere. Referring to the swine flu pandemic of 2009, he said, “Even with H1N1, we didn’t see this particular outcropping of social networking.”

Dr. Jeremy Nobel, an adjunct instructor at the department of global health and social medicine at Harvard Medical School, warned that the widespread ability to communicate comes with the equally powerful ability to manipulate, distort and censor information. As a result, he said, people under quarantine may be left to ponder if governments are telling the truth, creating tension between the comfort of interpersonal communications and discomfort of official ones. “In an era of fake news,” he said, “people might ask: What is fact, and what is truth?”

A Chinese doctor who blew the whistle in late December on the spread of the virus wrote to a chat group in his initial message, “quarantined in the emergency room.” The doctor, Li Wenliang, later died from the infection.

Shirley Lin, an advertising entrepreneur in Silicon Valley, was communicating regularly through a WeChat group with friends and colleagues in China who have family and friends in Wuhan, the epicenter of the virus. Ms. Lin said that when someone posted a video that included criticism of the Chinese government, it often disappeared before it could be seen by everyone in the group.

The surveillance became so worrisome that the group recently abandoned WeChat, which is owned by a Chinese company, in favor of an encrypted mobile phone service, like Telegram or WhatsApp. She said she preferred not to name the precise one to keep it below the government radar.

A small but growing body of scholarship backs up the idea that social interactions can stimulate reward centers of the brain and, in turn, dampen a stress response, and enhance resilience and even physical health. David Creswell, an associate professor of psychology at Carnegie Mellon University who works on that research, said that it stood to reason that smartphones, to the extent they are used to make welcome social connection, could diminish the stress of isolation.

James Katz, a professor of emerging media at Boston University, said: “Without contact, it’s solitary confinement, which is seen as a cruel and unusual punishment. Being socially cut off is a form of death, but a reversible form of death. Having the communication allows people to make the mental adjustment to reality.”

Eimi Yamamitsu in Tokyo contributed reporting.