Every fall you see the news reports, school notices, and health alerts about cold and flu season. Why is it this time of the year? The answer is in how cold and flu viruses spread.
Recent studies are shedding light on how cold and flu viruses develop across the country. If you get sick this winter, you’re in good company. Every year in America alone, there will be more than 1 billion colds reported resulting in more than 50 million missed workdays along with 60 million schooldays.
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The Geography of Colds
In the United States, the official "cold season" begins in late August when the number of reported cold and flu illnesses rises sharply and remains elevated until late April or early May.
2 At first, many scientists attributed this to the cold weather. However, this isn’t entirely accurate because it has been found that the "cold season" also occurs in warmer regions with rainy seasons.
Researchers at the Center for Infectious Disease Dynamics have presented strong evidence showing that different types of weather conditions, beyond just being hot or cold, serve as germ incubators, enabling viruses to spread and migrate as the different seasons change. In fact, they found that in places where the weather stays relatively constant, influenza activity stayed constant year round.
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Based on their findings, they proposed that the tropics might somehow serve as an "influenza reservoir in between influenza seasons." Or put another way, it seems we keep passing colds back and forth across the hemispheres like the great, big, global family that we are.
If cold and flu germs are able to survive in tropical and more weather-consistent areas, how does that relate to our annual cold and flu season? According to a 2006 Harvard study,
4 the missing link could be airplanes.
Germs and Airplanes
The Harvard study found that domestic airline travel volume in November, especially around the Thanksgiving holiday, was an accurate indicator of how rapidly a flu virus will spread. Their research was further supported by the delayed 2001 to 2002 flu season in correspondence to the decline in air travel after the September 11 terrorist attacks.
Basically, they found that airplanes allow people and germs to move across the country at a rapid pace. The combination of drier air and people spending more time indoors enables the germs to survive during these times of the year and migrate.
What You Can Do to Avoid Cold and Flu Germs
There’s no getting around it; germs will spread and the cold and flu season will come and go. But now that you know how it spreads, you can start to prepare your family and take the
right measures to keep cold and flu germs out of your home all year long.
1
Schachter, N. The Good Doctor’s Guide to Colds and Flu. p 2. 31 Oct 2006.
2
Ibid, p. 69.
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