The above video simulates the various parameters which are currently being used to actively fight the outbreak. It also better explains how if even some people don't follow the rules, the outbreak can effect as many as half the population. The video maker is not an epidemiologist, so just understand the trends and not the hardcore parameters. For those curious, Grant, or 3Blue1Brown, is a fantastic YouTube content creator and educator. You may consider his content to be a trusted source. Stay safe.