Work While Sick or Take Off??

According to WebMD, when we're sick with a common cold, we're not very productive, and employer health costs can be lost up to 60%.

http://www.webmd.com/cold-and-flu/cold-guide/common-cold-too-sick-to-work

Yet, many people still report to work while sick, exposing their coworkers to their illnesses.  Is this because the employee is afraid to take a day? Is there no coverage or a way that coworkers can take up the slack?

While I'm not a major advocate of taking the day off just to be off, I think that employees that are sick should stay home.  As an asthmatic, a common cold for YOU can quickly turn into an asthma attack for ME.  In addition, some people have weakened or compromised immune systems.

It may be an inconvenience for your employer to go without you for a day or so, but it would be an even bigger inconvenience if numerous people had to take off because they contracted an illness from a sick person that refused to stay home.  Just the same, I think sick children shouldn't go to school/daycare.  I know that's not always possible, but it sure would prevent other children from being ill.

Employers and employees, chime in.  What do you think are the best practices when it comes to sick days?