More than 1 in 4 Americans work even if they’re ill. Workers say they worry about lost wages, a backlog of work or punishment from their boss.

A survey by NSF International, a public-health testing group based in Michigan, found that 25 percent of people who went to work while sick said their bosses required them to. The group polled more than 1.000 adults during this year’s flu season. Thirty-seven percent of the people surveyed said they went to work while ill because they needed the money. Forty-two percent said too much work would pile up if they stayed home.

According to the Bureau of Labor Statistics, about 4 in 10 private-sector workers don’t get paid sick-leave benefits. That means they don’t get paid if they don’t go to work. This usually includes workers in retail and restaurants.

Twenty-five percent claimed they work while sick because their boss expects them to.