Your mom or dad probably told you to bundle up against frigid temperatures like the ones hitting much of the United States right now.
That's good advice if you want to stay warm and avoid frostbite or hypothermia -- but they were wrong if they thought they were protecting you against colds and the flu.
"Grandma was being good-hearted to tell us to put on mittens," said Dr. William Schaffner, an infectious disease expert at Vanderbilt University School of Medicine -- but a person is not more likely to catch a cold or flu because they're freezing, according to health experts.
That's because getting sick has much more to do with how people are exposed to cold and flu viruses.
In fact, there are two main theories for why cold and flu season peaks in winter -- and neither of them revolves around people being cold.
When a person with a respiratory virus coughs or sneezes, the virus escapes the host via a small droplet. In colder months, the virus can more easily remain in the air to infect another person, Schaffner said.
“When that moisture evaporates, that virus in its little core can be in the air for longer ... and then inhaled by party [two], which causes the infection,” he said.
It’s also likely that the more people stay indoors or in school, in close contact, the more chances viruses get to spread, Schaffner said.
“It may be a combination of those things,” he added. “[Influenza is] picking up right about now. It will usually peak in February.”
Dr. Stephen Morse, an infectious disease expert at the Columbia Mailman School of Public Health, said school rooms, in particular, can lead to outbreaks of the flu because children are packed together and haven't built up an immune response to combat different flu strains.
“Certainly, density, having people close together,” can help spread disease, said Morse. “Kids always have runny noses and are playing together.”
Schaffner added that that there is no truth to the myth that temperature changes will make people sick.
"Because cold and flu season occurs during the winter and we see the change in the temperature ... we attribute our infection to the change in temperature," Schaffner said. "But they're not causally related."
Most medical experts believe flu is spread mainly by droplets released when an infected person coughs or sneezes, according to the U.S. Centers for Disease Control and Prevention.
About 5 to 20 percent of the U.S. population is infected with the flu every year, according to the CDC. Deaths associated with the flu have ranged between 3,000 to 49,000 annually according to the CDC.
Schaffner said the best advice for people wanting to avoid getting sick this year is wash their hands often and be sure to get a flu shot.