It is interesting about the reinfections as this was noticed in China in the earlier part of the year, when people were recovering, testing negative, and then subsequently testing a weak positive again. At that time scientists were unsure whether this was a reinfection, or whether it was the body's reaction to viral debris left behind. No doubt the research will have advanced considerably since then.
The importance of this, of course, is that any attempts at achieving herd immunity are doomed to failure if catching the virus does not give any degree of lasting immunity. In the UK serious mistakes were made early on when a 'herd immunity' approach was advocated by Imperial College London and the government initially based its strategy on this. However, the model they were using to plot the likely course of the disease through the population was based on viral pneumonia, which did not act in the same way. Once this was understood, there was a sudden re-think because the new calculations revealed tens of thousands would die every month if nothing was done to halt the spread of covid-19. Hence the hurried announcement of lockdown at the end of March in a desperate bid to stop the surging cases becoming totally out of control.
