The Centers for Disease Control and Prevention relaxed many of its Covid-19 guidelines this week, shifting sharply away from several of the precautions, including quarantines and social distancing, that have long defined the pandemic.

The move was prompted by the fact that many Americans now have some immunity to the coronavirus — through a combination of vaccination and previous infection — and by the availability of vaccines, booster shots and antiviral medications that can reduce the risk of severe disease.

Part of the public health agency’s goal in issuing the new guidance was to streamline the recommendations and help people manage their own risk, officials said. But the guidelines are still complex and contain plenty of nuance.

Here are answers to some common questions about what the guidelines mean for you.

Do I still have to stand six feet away from strangers?

The C.D.C. has not abandoned the idea of social distancing entirely — instead, the agency suggests keeping a distance from others as one of many strategies that people can use to help reduce their risk.

The old guidelines recommended that people who were not up-to-date on their vaccinations “stay at least six feet away from other people” in indoor public spaces.

Now, the agency recommends that people “may want to avoid crowded areas” or maintain a distance from others in order to minimize their exposure to the virus. This precaution may be especially important for people who are at high risk for severe Covid-19, the agency noted.

Do I still have to wear a face mask?

The general mask guidelines have not changed. The C.D.C. still recommends that everyone age 2 and older wear a well-fitting mask in public indoor spaces when the local Covid-19 community level is high. People who are at high risk for severe disease should also wear a mask when their communities are at the medium level, according to the guidelines.

Nearly 40 percent of counties across the United States are at a high community level, according to the C.D.C.

What should I do if I’ve been exposed to the virus?

As a precautionary measure, the C.D.C. used to recommend that people who were not up-to-date on their vaccinations and had been in close contact with someone with Covid-19 stay home for at least five days, a practice known as quarantining. (People who were up-to-date on their shots did not need to quarantine if they were asymptomatic, according to the previous guidelines.)

The quarantine recommendation has disappeared, one of the biggest changes in the new guidance.

“Quarantines are sort of a blunt tool,” said Jennifer Nuzzo, the director of the Pandemic Center at the Brown University School of Public Health. “I do think we have to shift in how we think about controlling this virus.”

Now, people who have been exposed to the virus can continue with their daily routines regardless of their vaccination status, as long as they remain asymptomatic. However, they should wear a well-fitting mask for 10 full days, monitor themselves for symptoms, take extra safety measures around vulnerable people and get tested at least five days after exposure.

If you use an at-home antigen test, you may need to test yourself repeatedly. To reduce the risk of false negative results, people who have no symptoms should take at least three tests, each 48 hours apart, according to a new recommendation from the Food and Drug Administration. People who do have Covid-19 symptoms should take at least two tests 48 hours apart.

“Your viral load grows after you get infected,” said Dr. Michael Mina, a former Harvard epidemiologist who is now the chief science officer for eMed, which sells at-home tests. “It goes up, and that takes time.”

What should I do if I test positive for the virus?

Isolate at home for at least five days, and keep your distance from others in your household. This recommendation has not changed.

If you remained asymptomatic during your time in isolation — or if your symptoms are improving and you have been fever-free for at least a day — you can leave isolation after Day 5, according to the guidelines.

Previously, the C.D.C. recommended that people with Covid-19 wear a mask for 10 full days. Under the new guidelines, people can remove their masks sooner if they test negative on two rapid antigen tests, taken at least 48 hours apart. Others should continue to mask for 10 days.

People who experience moderate to severe illness, or have compromised immune systems, should isolate for at least 10 days, the agency said.

If symptoms return after isolation, people should start their isolation periods over, according to the new guidelines.

What does this mean for schools and offices?

In theory, the new guidelines could free many schools and businesses from some of the restrictive measures that have been difficult to enforce, including navigating a different set of rules for vaccinated and unvaccinated people. Quarantines have been especially disruptive and divisive in schools.

Under the new guidelines, children who have been in close contact with someone who has Covid-19 do not need to stay home, and schools do not need to administer frequent tests in order to keep these children in the classroom, an approach known as “test to stay.” Contact tracing and routine surveillance testing of asymptomatic people are no longer necessary in most settings, the C.D.C. said.

In reality, the new guidelines may not change much at many schools, which had increasingly been moving away from these measures. Massachusetts, for instance, dropped its quarantine requirements for asymptomatic children in May.

Still, some districts and officials do take their cues from the federal guidance, which could prompt some localities to relax their rules for the coming academic year.

“We welcome these guidelines,” Randi Weingarten, the president of the American Federation of Teachers, said in a statement on Thursday. “Every educator and every parent starts every school year with great hope, and this year even more so. After two years of uncertainty and disruption, we need as normal a year as possible so we can focus like a laser on what kids need.”

In an email to The New York Times on Friday, the New York State Department of Health said it was reviewing the new C.D.C. recommendations and would issue its own back-to-school guidance “soon.”

New York City’s Department of Health and Mental Hygiene said on Friday that it was also reviewing the new federal guidelines and still finalizing plans for the coming school year.

The C.D.C.’s guidelines said schools that are experiencing outbreaks may want to temporarily adopt additional precautions, including surveillance testing, contact tracing, mask-wearing and opening windows and doors to improve ventilation.