For years, scientists tried to contradict the advice handed down from grandmas everywhere: Button up or you'll catch a cold.

Medical experts speculated that the human immune system was less active during the winter months, which leads to the higher incidence of colds and flus.

But new research shows that the chilly weather itself -- rather than our sluggish immune systems -- contributes to the spread of cold and flu bugs.

According to an article at Live Science, evidence shows that cold and flu viruses remain stable -- and therefore transmittable -- when the temperature drops and relative humidity is low. If a person sneezes or coughs, viruses survive in the cold for a longer time, increasing the odds that others may inhale the viruses and become infected.

According to the Centers for Disease Control, some 200,000 Americans are hospitalized from influenza each year, and 36,000 people die from flu complications. They list dozens of ways to cope with winter bugs on the CDC's Seasonal Flu website. Here's a cheat sheet:

Wash Your Hands
The best way to fend of bugs is to wash your hands. As often as you can. If you can't use soap, experts recommend using an alcohol-based hand-sanitizer. Along with staving off viruses, this can also stop the spread of nasty bacterial infections, including MRSA, which has been making headlines of late.

Stop the Spread
To prevent the transmission of bugs, avoid touching your eyes, nose and mouth; always cover your mouth and nose when you cough; and (most important) stay home when you feel sick.

Focus on the Basics
A healthy lifestyle is the best way to strengthen the immune system, and you already know that this entails eating a nutrient-rich diet, getting lots of sleep and regular exercise, staying hydrated, and managing stress levels.

Next Steps
October and November are the time to get a flu shot or nasal vaccine. Or, if you're looking for natural alternatives, lots of people swear by vitamin C, echinacea, and goldenseal.

Protect Yourself in Germ Zones
Playgrounds, shopping carts, ATM machines, laundry, and even your handbag rank among the germiest places you're likely to encounter. Here's a quick overview of how to reduce your exposure to germs.

Finally, remember grandma's advice: Button up -- baby, it's cold outside.