NARRATION: Many states that relaxed quarantine measures are now seeing rising cases of coronavirus. And theres still the fundamental question about working in the midst of a pandemic: How do we stop people from getting sick on the job?

KESHIA M. POLLACK PORTER (DIRECTOR, INSTITUTE FOR HEALTH AND SOCIAL POLICY, JOHNS HOPKINS UNIVERSITY): I think there are really important lessons to learn from the past. The messages that we were hearing during the H1N1 pandemic were similar to what were hearing now, Stay home. Dont spread this to other people. And many people did not have a real choice to stay home. And were seeing that now.

ARCHIVAL (ABC NEWS, GOOD MORNING AMERICA, 10-25-09):ANCHOR: We begin with swine flu. Now widespread in 46 states.

NARRATION: In spring of 2009, a new H1N1 influenza virus, known as swine flu, was first detected in humans. That summer a pandemic was declared and it was in the fall, that the highest rates of infection were reported.

KESHIA M. POLLACK PORTER: Theyre going to work where theyre around other individuals, touching their face, inadvertently, touching doorknobs, high contact areas. You can see how that number can spread so easily. I, myself, was sick. I was supposed to travel for work. Being a public health person, I knew that that wasnt the best thing to do, to put other people at risk. I was able to stay home until I didnt have a fever anymore, until I felt better, because I worked at a place that provided that benefit. But for people who dont, I can see why thats such a hard decision to make.

ARCHIVAL (NBC, 11-10-09):ANCHOR: Well, if you get the H1N1 flu, should you stay home or go to work? It is a tough choice millions of Americans are making because they have no paid sick leave.

KESHIA M. POLLACK PORTER: We know that the workers who are most in need are least likely to have access to paid sick leave. Its 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.

ARCHIVAL (CBS, 11-11-09):KARA KNOCHE (WAITRESS): A week off of work would be really bad. Thats a whole, thats like rent.

NARRATION: And it turned out that about five to seven million people are thought to have gotten the H1N1 virus because their coworkers went to work sick with the disease.

ARCHIVAL (CBS, 11-10-09):NEWS REPORT: The federal government has been telling people who have fevers or sick kids to stay home to slow the spread of the H1N1 virus. It is believed the rate of infection could be cut by a third that is, if infectious folks didnt go to work or school until their fever was gone.

NARRATION: So Congress began debating a federal emergency paid sick leave policy, as well as the potential for something longer-lasting.

ARCHIVAL (CBS, 11-10-09):NEWS REPORT: According to Congress 57 million Americans dont have paid sick and medical leave, that puts the U.S. in the company of only a handful of nations that dont guarantee sick leave for citizens.

NARRATION: But there was also pushback against the measure, and some small business owners were especially concerned.

ARCHIVAL (CBS, 11-11-09):RESTAURANT OWNER: Its a huge challenge.REPORTER: Hugely expensive.RESTAURANT OWNER: Its a hugely expensive challenge to put on top of a restaurant, anytime, but especially in the current economy were in.

KESHIA M. POLLACK PORTER: When we look at what happened with H1N1, there were hearings, there were debates. And we still do not have federal paid sick leave policy.

NARRATION: But in recent years, low-wage workers have pushed some states and cities to pass their own legislation. And the difference between states that do mandate paid sick days and those that dont, has given researchers a window into the effect the policy can have on containing an infectious disease.

NICOLAS ZIEBARTH (ASSOCIATE PROFESSOR, POLICY ANALYSIS AND MANAGEMENT, CORNELL UNIVERSITY): So we see when we compare states that implement paid sick leave and compare them to states that do not, we find that influenza-like illness rates, or basically flu rates, decrease significantly in the next couple of months and even years.

KESHIA M. POLLACK PORTER: Were dealing with COVID-19 right now, but these issues are relevant for the seasonal flu, for other types of illnesses, other types of infectious diseases. So, paid sick leave would not at all stop Coronavirus from spreading. But what it could do is really help to contain the risk of transmission to other individuals.

NARRATION: In March, Congress passed emergency legislation, requiring some companies to offer paid sick leave through the rest of the year, and offering tax credits to cover those costs. But the bill excluded many people, including a lot of essential workers.

ARCHIVAL (NBC NEWS, 3-29-20):VANESSA BAIN (INSTACART LABOR ORGANIZER): A lot of us are literally making the decision between, you know, our health and our financial security right now.

NARRATION: But just having access to a sick day, doesnt mean someone will actually take it. In a survey that asked employees what they think of co-workers who come in sick, most people say that person is showing dedication to the job.

ARCHIVAL (CNN, 4-2-20):CHRIS CUOMO: My fevers gone up a couple of degrees in the last 30 minutes, nights are tough. Ive lost 13 pounds in three days.SANJAY GUPTA: We had suggested you not work right now. I mean, I know youre incapable of not working and talking about this, but just for the record we did suggest it.

DEBRA LERNER (DIRECTOR, PROGRAM ON HEALTH, WORK AND PRODUCTIVITY, TUFTS UNIVERSITY MEDICAL CENTER): Work is so important to most peoples lives. We live in a society where work is important to our material well-being, a central part of our identity, our creativity.

NARRATION: Employees say they often power through because taking a day off could affect job security. Those concerns have heightened during this pandemic when unemployment is at its highest rates since the Depression.

DEBRA LERNER: The current situation right now is, you know, so precarious in so many ways, economic insecurity is so high. When people may not be so sick that they have to be bedridden, that they might try to go into work, because the cost of not going to work or not continuing to be productive is so great.

NARRATION: And businesses are also struggling to stay afloat during a pandemic recession. Business groups have cautioned against making the 2020 expanded paid sick leave measure a permanent mandate.

ARCHIVAL (NBC, 5-7-20):MARC FREEDMAN (VP OF EMPLOYMENT POLICY, U.S. CHAMBER OF COMMERCE): Its very easy to say, Oh, gosh, paid sick leave is a wonderful benefit everybody should have it. I dont disagree. But is the answer telling every employer thou shalt provide it?

NARRATION: Unlike some countries that offer government support for paid sick leave, in the United States its largely left to the employer.

DEBRA LERNER: The workplace has an enormous role here that it doesnt quite have in other parts of the world.

NARRATION: Though there are debates about the economic impacts of paid sick leave policies, a recent review of studies of workplaces that were mandated to offer sick days found that most employers reported that it didnt significantly impact their bottom line.

DEBRA LERNER: Whether its through the workplace, whether its through state plans, health is important, work is important. And when we sit back and we look at how our policies create barriers to helping people to stay healthy, and helping workplaces to be healthy and productive, then we havent learned anything.