Implications for the rest of UK and Europe
The UK government last week, in response to spikes in the number of cases, increased the stringency of lockdown measures locally in the Northwest of England. Spain and France have also had recent local surges. What do these apparent peaks tell us about the spread of the virus and what is going to happen in the future?
How accurate are the data on how many people are infected?
- Clearly, the authorities can only know about the cases they have been told about. Given how many people will have no symptoms, or have mild symptoms but do not get tested, then the official figures are a substantial underestimate of how many people are infected in the population.
- Official data suggest that at the end of July there had been 300,000 cases in the UK (and interestingly a similar figure in Spain). Estimates from a population survey based on antibody testing published on 26 July by the UK Office for National Statistics suggest that about 2.8 million people have had the infection- this does not even include cases that arose in care homes and other non-residential settings.
- Thus probably only around 1 in 10 cases have been documented.
Does this mean that the local peaks recorded may not be accurate?
- We cannot know for certain the true number of cases in any area
- It is a reasonable presumption, though, that an increase in the number of known cases is likely to reflect a similar increase in the real number of all the underlying cases
- This is only true if the chance of being tested is similar in all parts of the country
- One possibility is that a flurry of cases in an area will lead to greater awareness and hence more testing – thereby possibly exaggerating the relative size of a local peak.
What are the data on the known cases in Manchester?
- There has been a doubling of the number of documented cases in the week ending July 31st compared to the week ending July 17th.
- Also, Manchester never had the same fall in cases as the rest of England following the peak of infection in April.
- In the graph below I have calculated the percentage drop in the number of recorded cases over the past 2 months compared to when the epidemic was at its peak in early April.
- Cases in Manchester dropped more slowly
- At the end of June, compared to the rest of the country there was a peak in cases, similar to the one we are seeing now
- So, accepting all the potential for inaccuracies, this new peak in Manchester is neither new nor unexpected
What do these figures tell us about the rest of the UK?
- Firstly, in the graph above, the data from England show no reduction of cases over the past 6 weeks
- Secondly, my analysis of the publicly released UK data showed that in the last 3 days of July there was at least one case reported in over 250 of the 314 administrative areas in the country.
- If the under-reporting is as above, this suggests that there could be pockets of at least 10 active cases throughout the country.
- Hence spikes like the current Manchester one could arise anywhere at any time
Is the pattern the same in the rest of Europe?
- Today there have been at least 100 new cases reported from 17 European countries
- Spain has seen rises in all 17 provinces but with peaks in Catalonia and Aragon
- France has seen an increase in spread as shown in the map of ‘R’ values published last week
- Covid-19 remains widespread throughout the UK and probably most countries in Europe
- Local peaks will continuously emerge
- But there are a number of lines of evidence to suggest that the severity and impact of the disease is not as great as it was in April. The data addressing this and the possible reasons will be explored in the next posting on this blog!