The PSA video producer compares cyber bullying to a virus because a virus can be spread easily, effectively,  etc. Cyber bullying, can also be spread easily and effectively. As soon as one person posts a comment on social media, mail, text message, or any other way of communicating online, other people will start joining in, and the victim the virus is effecting is weaker and weaker, meanwhile on the other hand, the virus is more and more powerful. This makes it hard for the victim to concentrate in school, home, or anywhere else. But you can stop cyber bullying. It all starts with just one little post, to defeat an entire virus.