European countries were the largest contributor of cases globally in March and April. As authorities introduced the necessary lockdowns, social distancing, testing and contact tracing, there were marked falls in deaths and the numbers of cases. The debate then moved to avoiding a second wave.
But in very few countries have cases completely disappeared and more worryingly there has been a surge of cases in many countries over the past few weeks. How substantive is this surge and what are the explanations?
What are the data?
- I have selected a number of large European countries, some with previously high and others with low level of infections.
- I have used the available data to compare the number of reported cases in the latest data (typically the second full week in August) with those in the equivalent week in July.
- I have calculated what is the relative size of any increase, as displayed in the results in the table below. For example, Denmark has nine times as many cases in the August, compared to the same week in July.
- Large relative increases are seen both in countries which have been considered successful at containing the outbreak, such as Greece, Germany and Denmark, and in countries with harder to control outbreaks, such as Spain and France.
- (Before the UK becomes complacent, the absolute rate of currently reported cases is still twice that of Germany)
Are these increases real?
- Despite seeming to validate a Trump comment, it is a truism that the more tests that are done, the more cases that will emerge
- The number of people with positive tests considerably under-estimates the true number of actual cases
- In broad terms though, the level of under-estimation is unlikely to have changed to such a degree over one month, given that all these countries had well established testing systems by July
- There is a ‘multiplier’ phenomenon. By this I mean the more cases that emerge in a place, the more people turn up for testing – because of either ‘track and trace’ systems or greater public awareness. But this would not explain why the past week has seen such an increase
- And why should all these countries show an increase in August?
- The media have correctly identified what are in fact common factors in these countries:
- Relaxation of lockdown
- Increased infection in younger people, who are socialising more
- Localised epidemics in various factories and work places
At the beginning of the outbreak, I had thought it was possible that:
- The virus might just disappear without explanation, as some argue was the case with SARS Cov-1
- The virus might just mutate to a less transmissible form
- The virus transmission could be stopped by strict public health measures effectively preventing any future cases – with such measures achieving the necessary consent in a modern liberal democratic state
I now believe that:
Despite what we were told at the beginning of the epidemic, as shown in this figure from the Economist………
- None of these will happen!
- Any reduction in the number of cases is temporary and once the lid is lifted, and there is greater direct human to human contact, spikes will continue to occur
- However successful any country has been in the past does not make them any more secure now
- For me now, the term”second wave” is meaningless. This current wave will be with us until we have a vaccine.
- We can change the shape of this curve but it will not come down to the level where the threat to public health has gone
Making sense of CoVid-19 with Silman 