How low are infection levels?

The level of infection in the UK has fallen significantly from the highs of early April. The Office for National Statistics (ONS) estimates that only 1 person in 1700 currently has the virus which means, at an individual level, the risks of catching Covid-19 are very low. This is clearly great news but if we look at case data from countries in the EU, we are far higher than all of them.

Cases per million

These countries had waited until infection levels were far lower than we did before they eased restrictions. This is because the higher the level of infection, the greater the risk of a widespread and rapid outbreak. As an individual it may appear much safer now, but that does not mean as a society it is also true, and so our individual risk might quickly rise again if easing restrictions leads to a rise in R.

If we look across the world, there are places with far worse infection levels. These are the countries with policies of very limited restriction and gives an idea of what the results of those policies are.

Cases per million

The US initially attempted to bring down infections with some form of lockdown, but some States gave up on this approach in early May and reopened despite levels of infection remaining high. In the US there are vast differences between States according to their policies and timing of first cases, with places such as New York seeing declines down to UK with others still seeing rising levels.

Cases per million

The chart below looks at Texas, Florida and Arizona together, a combined population of just below the UK. Case numbers in May were similar to the levels we see currently in the UK, and since reopening in May you can see the result with a rise to 10 thousand per day and rising ever more rapidly.

This is exactly what the UK needs to avoid.

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.


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. 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.