With jittery shoppers flocking to supermarkets to stock up on supplies for the coronavirus outbreak, some of the country's largest grocery chains are announcing measures to enhance sanitation and maintain supplies.

Across the U.S., hand sanitizer, toilet paper, sanitation wipes and canned goods have been flying off shelves as the number of confirmed coronavirus cases continues to climb.

With panic-buying gripping shoppers, Walmart, the nation's largest retailer by sales, announced this week that it has given store managers the "discretion to limit sales quantities on items that are in unusually high demand."

Target says it's cleaning surfaces such as checkout lanes and touch screens at least every 30 minutes. It is also placing sales limits on products like hand sanitizer, toilet paper, disinfectant wipes and bottled water.

Albertsons Companies, the owner of such chains as Safeway, Shaw's and Star Market, says it too will be imposing quantity limits on high-demand items like hand sanitizer and household cleaners.

Wegmans, which operates in seven states, posted a list of limited-purchase items, including diapers, household cleaners, bath tissue and packaged bread and rolls. Walgreens has announced similar policies.

Chains have also begun rolling out new hours of operation in order to clean stores and restock supply.

Whole Foods says it will modify hours and conduct "additional deep cleanings throughout the day." It is increasing its number of hand sanitizer stations and suspending its usual array of food samplings.

Walgreens says it too will be suspending food and drink sampling, and the chain says it will offer free delivery for purchases on its website.

Wegmans says it will not keep stores open past midnight. Publix, which has more than 1,200 stores across Florida and parts of the South, says it will be closing at 8 p.m. to give employees time to sanitize shelves and restock supplies.

Harris Teeter, a chain in the southeast, tweeted that starting Sunday, it will be closing stores at 9 p.m. each night in order to "focus on cleaning, replenishment, and the well-being of our valued associates."

Walmart says it too is considering changing the "hours at some 24-hour facilities to allow for additional cleaning."

Meanwhile, to help reduce the risk of the virus spreading in their stores, some chains are encouraging customers to skip the grocery aisles altogether. Instead, they're suggesting in-store pickup or home delivery.

Copyright NPR 2020.