For a co-worker showing flu symptoms, approach him or her "with care and concern, rather than that 'ew, ick' tone in your voice," Post says. She suggests something like, "I'm worried about you, and this seems like it could be the flu," followed by a polite prompt to go home or see the doctor.
As for those strangers – say, a fellow traveler coughing and sneezing into the open – asking them to cover their mouth or nose may be awkward, but Post points out it's a fair request. She suggests saying something like, "You don't sound so good. Would you mind covering your cough?" Offer hand sanitizer or tissues to them, too, if you have it. Just be sure to use a neutral tone, Post says. "You don't need to be their mother caring for them, and you don't need to have an attitude about it, either."
Teach your kids flu prevention. Parents, want to make sure your kid doesn't become the guy coughing sans covering, or (in the nearer term) the kindergartner picking up the flu and spreading it to classmates and their families? Get your children vaccinated, recognize flu symptoms and teach them flu etiquette. Just like you'd stay home from work if you're under the weather, keep your kids from school and activities if they're sick. Model preventative habits, such as hand-washing and sneeze- and cough-covering, too.
And if either you or a family member has flu symptoms, see your doctor. He or she may offer a prescription antiviral. However, keep in mind that, according to the CDC, antivirals are most effective if taken within two days of the sickness onset, so get moving.
[Read: Top Recommended Kids' Medicines.]