Overview: How a cold or flu virus works, and its effects on your body. The functions of congestion, a sore throat, sneezing, and coughing. The hosts explain why we get sick more often in the winter, washing hands for prevention, a comparison of a cold and flu virus, and the role of a fever, whether medications help. We take a look at the structure and function of living systems, particularly cells, and also the diversity and adaptations of organisms, regulation and behaviour of organisms, and immune response.