Herd immunity v Hrdlicka immunity — which one works?

For more than a year, the concept of herd immunity against COVID-19 has fuelled political and economic debate across the world. The idea: when a sufficient number of people achieve medically induced or natural immunity, we can all go about our business and even open up the borders.

Here's a definition: herd immunity occurs when a large portion of a community (the herd) becomes immune to a disease, making the spread of disease from person to person unlikely. As a result, the whole community becomes protected — not just those who are immune.

But we now have an Australian contribution to the debate thanks to the newish boss of Virgin, Jayne Hrdlicka, the most senior business figure to make the case that borders need to open even if "some people may die".