The problem there is, what happens when the rules are relaxed and people start going back to work and school etc, then the infections rise again, sharper this time. Obviously it'll be lockdown again or just ride it out. Either way, you're either going to cripple the economy or cripple the NHS. So what do we do? Let everyone out, go the herd immunity route, face a massive influx of patients into hospitals, struggle and crumble under the strain, leading to maybe hundreds of thousands of deaths, lots of people sick and off work? It's a tough choice, and the economy is going to suffer either way.