(NC) — It's back-to-school time, and with kids trading the contents of their lunchboxes, they'll be swapping more than sandwiches.

According to Dr. Alan Kaplan, Chairperson of the Family Physician Airway Group and Executive member of the International Primary Care Respiratory Group, “Every year like clockwork, two weeks after kids go back to class, the cough and cold season starts with a bang.”

“It's no surprise that respiratory infections spike when people suddenly change their routines, diets, and sleeping patterns, which makes them more susceptible to infection, and then gather together in small rooms for hours on end,” continues Dr. Kaplan.

Dr. Charles Gerba, a professor of environmental microbiology, led a research project on hygiene in schools which found that 50% of the classroom surfaces they examined were hosting some sort of virus.

“With those kinds of opportunities for transmission,” adds Dr. Kaplan, “it's no wonder that, on average, 200,000 schooldays are missed because of illness in Canada every month.”

And it's not just the young ones getting sick. Students of all ages dutifully bring home all the germs they've collected in school, and generously share them with their families. After collecting their own infections, parents and siblings then inadvertently spread the bugs to their friends and coworkers throughout their own days.

“People infected with rhinovirus or influenza are contagious starting about 12 hours before they even start to feel any symptoms,” says Dr. Kaplan, “making it very difficult to prevent spreading those viruses around.”

From schools to homes to workplaces, it's easy to track the impact of these inconvenient infections. According to a report by the CBC, colds and flu are estimated to cost the Canadian economy more than $1 billion per year in healthcare costs and lost productivity due to sick days.

There are steps you can take to reduce your likelihood of getting sick: avoid doorknobs and elevator buttons, and wash your hands often. For adults and children over 12 years, supporting your immune system before you get sick by taking Cold-FX is a good strategy. People without contraindications should also consider getting the annual flu shot.

Most of all, draw a bright red circle around September on your calendar. When the kids go back to school, they'll probably bring something home with them soon after. Cold and flu season starts earlier than you might think, but with a strong prevention strategy, you can stay healthy right through until spring.