It is all too easy to become fatalistic when faced with a massive problem like COVID-19. One could just assume that there is nothing we can do; all the deaths and economic destruction are inevitable and we just have to get on with things. I do not agree. Good policy is possible and the contrast between the approach of the UK and NZ is a useful demonstration of this.
The chart below compares actual daily deaths in the UK (orange) with a projection for the next few months (blue). The timing and size of the initial peak were dictated by the decision to go into lockdown on March 23rd. As inputs to the projection, I allow R0 to stay around 1 for a few weeks and then creep up to 1.3. From early June daily deaths begin to rise rapidly again; if we want the next peak to be at a similar level to the last, then a further lockdown will be required soon.
As an alternative scenario, let’s look at the model if we had gone into lockdown on March 9th. This was the date that Italy went into lockdown whereas here in the UK, Boris Johnson spent the Daily Briefing explaining that he was still shaking hands with everyone, including COVID patients in hospital.
Blue again is the model, this time based upon the earlier lockdown assumption; orange actual deaths in the UK. The difference may appear shocking but comes directly from the exponential growth of virus cases. As opposed to peaking around 1,000 deaths, we would have peaked at below 200. Rather than the current many hundreds of deaths per day, we would have perhaps 10.
This exponential growth has some simple intuition around it. Early on during the 2-week period when we were told to wash our hands, but not to socially distance or stay home, I estimate R0 to be 2.0. R0 of 2 means the number of infections doubles every 5 days – therefore in 2 weeks the number of infections would double 3 times i.e. 2, 4, 8 –2^3. If instead the R0 were 0.8, then the number of people infected would change by a factor of (0.8)^3 – which is to roughly halve. Comparing these, entering lockdown earlier would have halved cases rather increasing by a factor of 8 – a total of a 16-fold impact on the number of cases. This is why the blue line above is so much lower than the orange line.
The impact of this decision has not just been seen in the extra tens of thousands of deaths, it also makes a huge difference in how we can loosen the lockdown. In the projection above, I still assume a post lockdown R0 of 1.3. If the overall level of infections is much lower, then in absolute terms the growth in the virus is hugely lower. This would mean we would have far more room to experiment with lockdown easing measures such as school reopening without risking an imminent large outbreak.
This scenario shows to me that policy choices really matter. The example of NZ where they did exactly this shows that it is possible in the real world. They went into lockdown BEFORE they had their first death from COVID. The infection levels were low and now they have effectively eradicated the virus with a total of 21 deaths. This is why the UK government does not want to talk about international comparisons or mistakes they have made. We had plenty of warnings and examples from other countries on what we should do, but the UK has made catastrophic policy decisions that have cost tens of thousands of lives and made it hard to contemplate the removal of the lockdown. However, we do not have to continue making terrible decisions and better policy is possible.