When will the lockdown end?

This is the question I am asked most often. In an effort to look beyond all the government and media confusion on the issue, I have built a simple model to predict what the next phase looks like.

The data from countries which implemented a lockdown relatively early has been encouraging, in that a lockdown does stop the spread of the virus. Medical evidence seems to show the average time from infection to death is around 3 weeks, so it follows that peak daily deaths should occur around 3 weeks after the implementation of the lockdown. This is exactly what we are seeing in Spain and Italy.

It would suggest that peak deaths in the UK will be on April 13th.

Here is a summary table. Green cells are actual data and yellow are forecasts. Bear in mind that the “actual” data is often of very low quality and the forecasts should similarly be taken with large error bars.

Screenshot_2

For the forecasts in yellow to be accurate we assume the effectiveness of a lockdown is the same in each country. However, there are different levels of lockdown in place and perhaps more importantly there will be different levels of adherence and enforcement. For example, if some US states are less compliant then peak deaths would be later and much higher.

There is a helpful US report on how the lockdown measures could be relaxed and the preconditions for doing so. https://www.aei.org/wp-content/uploads/2020/03/National-Coronavirus-Response-a-Road-Map-to-Recovering-2.pdf This shows the aim is to move to Phase II, where schools and businesses can be reopened, while likely maintaining some level of social distancing to keep the strain on health care services within limits, until eventually a vaccine is produced.

Spain has already announced its intention for the first stage of lockdown relaxation to occur on April 11th when non-essentials workers will be allowed back to work. In the UK we are hearing speculation from Ministers that perhaps schools could reopen after Easter.

This seems optimistic. The report gives four sensible, simple guidelines to trigger relaxation in restrictions. The first two are relatively straightforward.

A state can safely proceed to Phase II when it has achieved all the following:

  • A sustained reduction in cases for at least 14 days,
  • Hospitals in the state are safely able to treat all patients requiring hospitalization without resorting to crisis standards of care

I would estimate some restrictions in the UK could be relaxed on April 27th and in the US by 7th May. But the final two are much more difficult.

  • The state is able to test all people with COVID-19 symptoms
  • The state is able to conduct active monitoring of confirmed cases and their contacts

This is what China and S Korea have been doing and we will be able to monitor how well this goes. However in the west, particularly the US and UK, it seems far away from being technically or politically possible to achieve.

The aim of all these measures is to suppress R0, the rate of transmission of the virus. Before the lockdown, this was estimated by the Imperial study to be as high as 3 in the UK. This means each patient on average infected 3 other people. This figure to get below 1 to control the spread. The experiment in China and S Korea is to see if this can be done through testing and contact tracing rather than lockdown.

In the UK and the US, I have not seen any movement towards this policy, which leaves me having to imagine what the plan might be. The UK has had high hopes for an antibody test, despite the 17.5 million they bought not actually working. The health secretary Hancock has just announced that he is hoping the private sector will somehow develop one. This does not qualify as a plan to me but I do hear echoes of the Brexit plan for N Ireland, which is to rely on technology that does not currently exist to solve difficult problems on an impossible timeline.

Perhaps the plan is as simple as reopen, hope for the best and deal with the next crisis when it happens. This would again be consistent with the UK government approach to Brexit. Another plan might be to reopen and move back into lockdown on the next spike in cases. Repeating rolling lockdowns until we have herd immunity i.e. when most people have already had it, or until the vaccine whichever comes first. This feels a bit like someone blowing a whistle and asking us to “go over the top” on a regular basis.

When does lockdown end?

The political and economic pressure to end the lockdown is immense and is only going to grow. I think that we will reduce lockdown restrictions, but I fear that we will not have a plan in place to stop the next wave of the outbreak.

 

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