Cough, Cold & Flu

Different Types

Over 200 different viruses are responsible for cold symptoms, including rhinoviruses, whose 100 different varieties cause most colds in early fall, spring and summer, and corona viruses, which cause most colds in the winter and early spring.

The flu is caused by 3 different viruses: influenza types A, B and C. Both influenza A and B are included in each year's flu vaccine. Influenza type C is not included because it causes a very mild form of the illness and may even not cause any symptoms. Types A and B are both constantly changing to evade the human immune system, which is why people are susceptible to the flu throughout their lives.