There’s nothing more selfish an employee can do than come to work sick. They may get a gold star for showing their sniffling faces at the office and soldiering through the workday to prove their value — but everyone around them just gets sick.

When people bring their infectious illness to work, it spreads — and when sick people don’t have a financial incentive to show up to work, fewer people get sick, according to a new working paper by the nonprofit National Bureau of Economic Research in the US.

The researchers studied US cities with paid sick-leave mandates and, using Google Flu Trends data at the city and state level from 2003 to 2015, looked for changes in flu rates after those mandates went into effect.

The cities that adopted paid sick-leave mandates in that time frame saw flu cases drop about5% after their laws took effect. For a city of 100,000 people, that comes out to 100 fewer infections per week, the study found.

"You see people who are at the workplace sneezing and potentially infectious. That’s how diseases spread," says Nicolas Ziebarth, an assistant professor at Cornell University and one of the study’s researchers.

For most people,staring at a computer through a fog of illness is torture, and does nothing to help them recover. Yet 3-million people, or 2% of the US population, bring their ailments to work each week.

Many do so because of financial pressures; nearly a third of US workers have no access to paid sick leave, according to the Bureau of Labour Statistics.The other two-thirds, who have the luxury of taking a sick day, need to stop making excuses for showing up at work sick.

Almost half of workers say they worry work will pile up if they stay at home sick. People who find their jobs engaging also have a hard time staying at home, finding work morefun than submitting to the reality of a sick day.

"Some people want to appear tough and signal that they are hard-working," Ziebarth says.

But those diligent workers aren’t just showing their commitment, they’re also showering their co-workers with germs; the modern open office plan is a breeding ground for contagious illnesses. Worst of all, people tend to come to the office at the beginning of an illness, when they’re at their most contagious, but still feeling well enough to get a little work done.

"You have over-the-counter drugs that suppress your symptoms, but they don’t suppress contagiousness," Ziebarth points out.

Employers, for their part, should encourage ailing workers to stay at home. Presenteeism — showing up at work ill, whether they’re contagious or not — costs companies about $150bn a year, one study estimates.

Workers are about a third as productive when they are slumpedin a desk chair working at half-speed as they are when they are healthy, say researchers. By staying at home when they are sick, they can get better faster. The rest of the workforce can remain infull — and fully productive — health.

And diligent workers who must meet a deadline or finisha life-or-death project should at least self-quarantine.

Telecommutinghas become an increasingly acceptable way to work, and 60% of US employerslet employees work from home, according to the Society for Human Resource Management’s annual Employee Benefits Survey.

"It’s good to change the culture of how people see each other. You can signal hard work in a lot of different ways. It’s not the right way to go into the office and spread diseases," Ziebarth says.

All employees need to play their part in stigmatising colleagues who come to worksick to protect their own health and their own incomes.

Bloomberg