Has this Brazilian city reached herd immunity without lockdown?
From our UK edition
Throughout the Covid crisis, the international response to the disease has rested on a simple assumption: that none of us have any resistance to it, being caused by a novel virus. Therefore, if allowed to let rip through the population, the virus would exponentially spread until around 60 – 70 per cent of us had been infected and herd immunity was reached. This was the assumption behind Neil Ferguson’s paper in March, claiming that Covid-19 would kill 500,000 Britons if nothing was done and 250,000 of us if the government carried on with the limited mitigation polices it was then following. Yet real world data has challenged this assumption.