Here are some insights from infectious disease specialists:WHAT IS HERD IMMUNITY? ** Herd immunity refers to a situation where enough people in a population have immunity to an infection to be able to effectively stop that disease from spreading. ** For herd immunity, it doesn’t matter whether the immunity comes from vaccination, or from people having had the disease. This means that, if no other measures are taken, herd immunity would kick in when between 50% and 70% of a population is immune. The “sweet spot” he added, is when one infected person infects, on average, one or less than one other person.

Source: The Express Tribune March 19, 2020 19:41 UTC