They are a new class of emergency medical workers: the more than two million Americans reporting to work each day to sell food and other household staples to a country in the midst of a coronavirus pandemic.

As shoppers swarm stores, snapping up everything from milk to toilet paper, cashiers are there to ring them out. Stockroom employees replenish shelves as soon as shipments arrive. Their presence is a source of calm, signifying that, even as demand has surged, supply chains remain intact and the essentials that people need remain available.

“Workers in food stores are the ones keeping this nation from going into civil unrest,” said John T. Niccollai, president of Local 464A of the United Food & Commercial Workers, which represents 16,000 food workers in New York and New Jersey, including those at ShopRite and Key Food. “Because if there is no one working in the stores, we are in trouble.”

But these same employees are tired and, because they constantly interact with customers, fearful of getting sick themselves. Workers at a number of retailers say they are being denied medical supplies like protective masks and gloves, because their employers insist the gear is unnecessary and could stoke fears among customers.