The following graph might help illustrate some issues with lockdown relaxation. First, the graph itself.

The deaths in the lockdown line assume the lockdown is maintained & in lockdown the reproduction rate of the virus has fallen to 0.67 (some studies have it as low as 0.62). Numbers trail away, but the crisis continues indefinitely.

Next, suppose lockdown were ended on April 30 but we maintained fairly strict social distancing rules, succeeding in having the virus double in infections only every 8 days as vs the 3.5 in early March. That might not hv bn v different from where we were just before lockdown.+

If we also assume the NHS could cope with about 2.5 times as many serious cases as it had at the current peak, that gives us the grey line. Herd immunity is achieved in early June &, with a lag, deaths trail off & then fall away to a low level.+

If we had even stricter restrictions after a 30 Apr lockdown were released, so cases doubled only every 14-15 days, we'd reach herd immunity in mid-June & by late-June deaths would have peaked, as per the orange-red line.+

Note that in both the lockdown removal cases, total deaths by end-July are around 125k.

The 125k relies on the case fatality rate being 0.3% instead of 0.6% with the vulnerable shielded. If easing lockdown led to less effective shielding of the vulnerable, that 125k would rise.

This, then, is the conundrum: unless we believe we can devise societal protocols that eliminate almost all difference btwn how CV is transmitted whilst we're in lockdown & post-lockdown, easing lockdown is a herd immunity strategy that will issue in 125k+ deaths.

Even with greatly curtailed spread, we would be likely to achieve herd immunity well before any therapy or vaccine were available if lockdown were relaxed, unless there are extraordinary restrictions placed on our activities even post-lockdown.

Now my feeling is that we probably ought to be willing to accept many tens of thousands of extra deaths to escape our current predicament. But politicians need to be honest with the public & commentators need to explain that reality to them.