The last time the U.S. experienced a pandemic, advice to working Americans was similar to the message officials are sharing today—stay home.

Similar to today’s COVID-19 outbreak, the 2009 H1N1 pandemic laid bare issues of inequality in the U.S., including disparities in paid sick leave. In 2009, the federal government did not have a federal paid sick leave policy, and it still doesn’t today, forcing U.S. workers to make the impossible choice between financial and personal health. But there are important lessons we can learn from the past, says Keshia Pollack Porter, director of the Johns Hopkins Bloomberg School of Public Health Institute for Health and Social Policy.

“We know that the workers who are most in need are least likely to have access to paid sick leave,” Pollack Porter tells TIME and Retro Report. “It’s overwhelmingly low income workers, workers of color, people who work in small businesses, that just tend not to have access to these types of benefits.”

In 2009 the federal government considered an emergency paid sick leave policy in order to help contain the spread of H1N1. Although in the end, the federal government did not implement the emergency measure, many states began adopting one of their own, allowing researchers to study its impacts.

Not surprisingly, influenza-like illness rates decreased significantly in states that implemented a paid sick leave policy compared to states that didn’t.

But even with access to sick days, U.S. workers might still show up for work when sick because of cultural expectations. “We live in a society where work is important to our material wellbeing, a central part of our identity, our creativity,” says Debra Lerner, director of the Tufts Medical Center Program on Health, Work and Productivity.

As in 2009, employers today are grappling with an influx economy, and the burden of paid sick leave in the U.S. often falls on that employer, causing added financial pressure, an issue that only exists in a handful of countries around the world.

“Whether it’s through the workplace, whether it’s through state plans, health is important, work is important,” Lerner says. “When we sit back and we look at how are policies create barriers to helping people to stay healthy and helping workplaces to be healthy and productive, then we haven’t learned anything.”