Researchers Discover Why Flu Travels in Cold Weather

Influenza is an Italian word from the 18th century, and some historians say it's part of a phrase, influenza di freddo, or "influence of the cold." In any case, flu season tends to be in the winter. In the northern latitudes, that's November to March; in southern latitudes, it's from May until September, which is their winter. In the tropics, there is not much flu at all. Researchers have always wondered why and now they think there's an answer. Dr. Samira Mubareka is co-author of the Mount Sinai School of Medicine's report into the connection between airborne flu and seasonality.