A round of high fives after a successful sales call this month could be the start of something big: big numbers of salespeople calling in sick with the flu, passed from palm to palm to nose. In a restaurant break room, a sneeze from one employee can trigger weeks of sniffles and fever among co-workers. These daily run-ins on the job sideline a lot of us, particularly at this time of year. But those who are passing germs around are often doing so because they do not have paid sick leave.

Data published in 2013 by the U.S. Centers for Disease Control and Prevention indicate that one in five restaurant workers clocked in even when they were suffering from diarrhea and vomiting, the two main symptoms of norovirus. That formidable group of nausea-inducing viruses causes about half of all foodborne illnesses in the U.S. Bringing those harmful microbes into the workplace puts customers at risk. Employees also infect other staff members and force their bosses to scramble with a costly deluge of absences. When swine flu broke out in a 2009 pandemic, eight million infected American adults still went to work. Those employees may have caused another seven million flu infections, according to estimates by the Institute for Women's Policy Research. Together, that adds up to one out of every four people who caught the disease that flu season.

Many of these workers cannot afford to stay home. Roughly 75 percent of part-time workers in the U.S. and 25 percent of full-time employees have no paid sick days. It is time for that to change. We need laws that increase the number of people who can take time to see a doctor or stay home with the flu without having to sacrifice a day's wages.

Pushing employees with the flu or a stomach bug to drag themselves into the office means more absences, not fewer. Workers who are not able to take paid time off to see a doctor are more likely to take six or more sick days a year than are those who can take time off, according to a 2005 Commonwealth Fund report. Overall, workers who are ill while on the job account for anywhere between 18 to 60 percent of workforce productivity losses, according to a 2004 review of estimates in the Journal of Occupational and Environmental Medicine. cdc data also show that employees without sick leave are more likely to get injured on the job and are less likely to get preventive health screening for cancer.

Experience suggests that paid sick leave does not hurt the bottom line. Sixteen U.S. cities and the states of Connecticut, Massachusetts and California have passed regulations that typically allow workers to earn one hour of paid sick leave for every 30 hours on the job. A 2013 audit by the city of Washington, D.C., found no evidence that its five-year-old paid sick leave law had prompted businesses to leave the area or discouraged new companies from coming in. On the West coast, San Francisco continued to outperform nearby Bay Area cities in job growth after it implemented a paid sick leave law in 2007. There are expenses: employers have to bear a small increase in base pay for employees who use leave, for instance. But productivity and public health benefits outweigh these costs.

Many opponents of laws to require more paid sick leave say that healthy workers will abuse the benefit, resulting in mass absences. But a study of Connecticut's experience by the Center for Economic and Policy Research shows this fear is unfounded. Still, the specter of empty workplaces has helped kill many proposals for minimum numbers of sick days. States and municipalities should follow the science, not the specters, and act now to require paid sick leave. It would be good for all of us.