Target, Walmart, Disney and others are relaxing their mask policies.

Target on Monday joined a growing list of retailers, restaurants and theme parks that will allow fully vaccinated customers to go mask free, following new coronavirus safety guidance from the federal government last week that said vaccinated people rarely transmit the virus.

[Answers to your questions about vaccines and masks at work.]

The Centers for Disease Control and Prevention on Thursday took many businesses by surprise when it said that people who are vaccinated could go maskless in most places, including indoors. For businesses, the announcement was complicated by the fact that C.D.C. guidance does not override state and local rules. But several major companies have already moved to relax mask requirements. Businesses for the most part have not said they would require customers to show proof that they have been vaccinated.

Here’s the latest on companies that are changing their mask policies.

Costco

Costco, which has more than 500 U.S. stores, said it would allow fully vaccinated customers to go mask-free where state and local guidance allowed. The retailer said it would “not require proof of vaccination” but would ask for its customers’ “responsible and respectful cooperation with this revised policy.”

Publix

Publix, which has 1,270 grocery stores in the Southeast, said “face coverings are optional for fully vaccinated individuals inside Publix stores” subject to local regulations.

Starbucks

Starbucks, which has 32,000 cafes worldwide, said that facial coverings would be optional for vaccinated customers beginning on Monday, unless local regulations required them. Employees at Starbucks locations in the United States and Canada will still be required to wear masks.

Target

Target, which has 1,909 stores in the United States, said it would no longer require fully vaccinated customers and employees to wear face coverings, except where required by local ordinances. The retailer said that it masks would still be “strongly recommended” for both shoppers and staff members who were not fully vaccinated.

Trader Joe’s

Trader Joe’s, which operates 517 grocery stores across the country, said that customers who were fully vaccinated no longer needed to wear masks in its stores. It will not require proof of vaccination “as we trust our customers to follow C.D.C. guidelines,” a spokeswoman, Kenya Friend-Daniel, said in an email. Masks are still required for store employees.

Walmart and Sam’s Club

Walmart said that vaccinated customers were allowed to go maskless starting May 18 in areas that did not have stricter mandates. A spokesman for the company, which operates more than 4,000 Walmart and nearly 600 Sam’s Club stores in the United States, said it expected its customers to abide by the honor system. Employees can also go mask-free by answering “yes” to a vaccination question that is part of a daily health assessment.

Disney parks

Walt Disney World Resort in Florida said that it was no longer requiring visitors to wear masks in most outdoor areas as of this weekend, though masks are still required in indoor locations. Disneyland in California continues to require masks indoors and out because of state mandates. Disney’s chief executive, Bob Chapek, said on an earnings call Thursday that the company had begun to increase capacity and that the C.D.C.’s new guidance “is very big news for us, particularly if anybody’s been in Florida in the middle of summer with a mask on.” About 150 million people visited Disney’s parks in 2019.

Hershey Park

Hershey Park in Pennsylvania said it would no longer require masks nor social distancing for fully vaccinated guests. The theme park, which drew 3.4 million visitors in 2019, said it would rely on its guests to “accurately follow the guidelines based on their vaccination status.”

Universal Studios

Universal Orlando Resort said masks were no longer required when outdoors but still must be used in “all indoor locations.” Its theme park in California will still require masks both outside and inside because of the state rules.