Andrew Yang, a leading New York mayoral candidate who has pursued extensive in-person campaigning amid the pandemic, announced on Tuesday that he had tested positive for the coronavirus.

“After testing negative as recently as this weekend, today I took a Covid rapid test and received a positive result,” Mr. Yang said in a statement. “I am experiencing mild symptoms, but am otherwise feeling well and in good spirits. I will quarantine in accordance with public health guidelines and follow the advice of my doctor.”

Perhaps more than any other candidate in this year’s race, Mr. Yang has sought to forge an in-person campaign trail, holding multiple events outdoors since declaring his candidacy last month.

His approach has generated enthusiasm on the ground and attention in the news media, but even before Mr. Yang tested positive, the risks were clear: A staff member tested positive less than a week after he announced for mayor, forcing the candidate to quarantine.

But Mr. Yang had since returned to a robust in-person schedule. He said his campaign had begun the contact-tracing process.

“During this time, I will continue to attend as many virtual events as possible, in addition to working with our incredible campaign team to continue our mission of getting New York City back on its feet,” Mr. Yang, 46, said in the statement. “When the time is right, I look forward to once again hitting the campaign trail and advancing a positive vision for our city’s future.”

In addition to the health considerations, the developments offer a vivid illustration of the campaigning challenges facing the mayoral candidates as they scramble to stand out before June’s Democratic primary. Many worry about their ability to connect over livestreams and wonder about how many voters they are truly reaching with virtual events. But the health risks — to the candidates, their staffs and their supporters — remain real.

Scott M. Stringer, the city comptroller whose mother died of complications from Covid-19, and Maya Wiley, a former counsel to Mayor Bill de Blasio, have both had to quarantine recently, though they have generally been far more cautious about in-person campaigning.

Pursuing a vigorous in-person schedule also may carry some political risk, especially in a Democratic primary.

Throughout the presidential campaign, the Democrats drew sharp contrasts with their Republican rivals over the matter of taking the virus seriously. President Biden’s staff members argued that by pursuing a lighter in-person campaign schedule, they were respecting scientific and medical recommendations and offering a glimpse of how Mr. Biden would lead the country through the pandemic — contrasting with President Donald J. Trump’s large in-person rallies.

None of the Democratic mayoral hopefuls are holding large rallies, though Eric Adams, the Brooklyn borough president, has faced criticism for fund-raising indoors. But they do face the challenge of breaking out of a crowded field while also signaling that they take seriously a pandemic that has devastated the city.

In an interview, Mr. Stringer wished Mr. Yang a quick recovery, but he also cast the development as a “wake-up call” to the mayoral field — a sign that some of the candidates are increasingly willing to draw mild contrasts with one another, and in particular with Mr. Yang.

“This is a dangerous business now, as long as this virus is raging, and we do have a special obligation to keep our people safe,” Mr. Stringer said.

“Nobody wants to see, you know, a colleague get sick,” he added. “But you don’t want to be the one to expose people. So, you know, whether it’s indoor fund-raising or up-close campaigning, we have to write new rules to keep people safe while we inoculate as many people as possible.”

A spokesman for Mr. Adams declined to comment on the reference to indoor fund-raising. In a statement, Mr. Yang’s co-campaign manager, Sasha Ahuja, said that the team’s strategy is informed by public health guidance.

“We hope every other campaign does the same and does as much or as little as they are comfortable with,” the statement said.

On Twitter, Mr. Yang used the moment to suggest a balm to speed his recovery.

“In all seriousness if you want me to feel better donate to my campaign!” he wrote. “Then I can relax.”