Some liken their job to working in a war zone, knowing that the simple act of showing up to work could ultimately kill them. At least 41 grocery workers have died so far. They include a Trader Joe’s employee in New York, a Safeway worker in Seattle, a pair of Walmart associates near Chicago and four Kroger employees in Michigan, as well as employees at meatpacking plants and food processing facilities around the country. Thousands more have tested positive for the virus.

Now workers across the country are staying home or quitting altogether, according to interviews with more than a dozen employees, leaving many markets short-staffed and ill-prepared to deal with demand. That’s complicated the scramble led by Walmart, Kroger and Safeway to fill hundreds of thousands of new jobs. Demand for groceries has doubled in recent weeks, employees say, as Americans avoid restaurants and prepare most of their meals at home.

Job postings for grocery clerks have jumped 60 percent in the past four weeks, according to Julia Pollak, a labor economist for the site ZipRecruiter. Supermarkets are increasingly hard-pressed to find and keep staff. Workers are walking out, going on strike and circulating petitions aimed at getting companies such as Amazon, Trader Joe’s and delivery service Instacart to take additional measures to protect their health.