Why is it so hard to cure the common cold?

On average, adults catch more than 150 colds throughout their lives. Even with similar symptoms, the cause could be different each time. Common colds are caused by at least 8 different families of virus, each of which can have its own subtypes. How can so many different viruses cause the same illness? And is a cure even possible? Explore the two main strategies we employ to fight viruses. [Directed by Anton Bogaty, narrated by George Zaidan, music by Nikola Radivojevic].