As governments have struggled to kill the spread of the coronavirus, policies have varied. Herd immunity - followed by countries including Sweden - has come under scrutiny. The strategy assumes a large section of the population will inevitably be infected whatever is done. Rather than enforce lockdown measures, herd immunity encourages social distancing in public places. The aim is to have as many low-risk people infected as possible. Immune people cannot infect others. Therefore, the more there are, the faster we kill its exponential growth, and the easier it will be to treat the vulnerable. The WHO has criticised the approach, as have many others. Is the Swedish government correct?