COVID-19: Case-Watch as at 22nd October

The UK Government introduced a 3-tier COVID-19 alert system, with each area in England being classified as “Medium”, “High” or “Very High” alert, depending on the cases in that local area.

Since last week’s blog, a large number of regions, including the likes of London and Essex, moved from the “Medium” level to the “High” level. While initially only Liverpool was in the “Very High” level, Lancashire was moved to this level from last Saturday, and South Yorkshire is due to transition this Saturday. Somewhat more controversially, after prolonged negotiations with local government were unable to agree on a financial support package, the Greater Manchester area is nonetheless moving to “Very High” level from this Friday (23rd). In this blog we consider whether there are other areas in England which might soon climb to the “High” or “Very High” alert levels.

Elsewhere in the UK, the Scottish Government is finalising plans for a similar tiered alert system to England, which is expected to come into force at the start of November. In the meantime, the temporary restrictions on hospitality has been extended across the country, with tighter restrictions across the more populous central belt. Meanwhile, Wales is implementing a two week “firebreak” of national restrictions from this Friday, following on from Northern Ireland, which is in the middle of its own four week “circuit breaker.”

We consider whether there are any early signs that these additional restrictions are helping to slow the spread of COVID-19, and if there is evidence that the restrictions should be expanded to other areas.

The overall picture on case numbers

The chart below shows the latest case numbers published by the UK government (as of the morning of 22nd  October). The bars show the daily numbers of new COVID-19 cases across the UK, whilst the line shows the running seven-day average, smoothing through dips in new case numbers which tend to happen at weekends and bank holidays, for example.

It is important to note that the case numbers over recent months (on the right of the chart) are not directly comparable with those from earlier in the pandemic (the left of the chart).  The limited testing capacity in March and April means it is very likely that true case numbers at that time were much higher than shown in the chart. Daily testing capacity is now 10-15 times higher1 than at the start of the pandemic. In addition, the implementation of “Test and Trace” means that more asymptomatic individuals are now being tested, and positive test results now include individuals with only virus residues i.e. who have not been infectious for many days and potentially weeks. The level of adjustment needed for comparability is not at this stage clear, however the dramatic rise in recent weeks continues to cause concern.

The sharp drop in more recent days shown in the chart is primarily due to the time-lag in obtaining testing results, as the figures are based on the specimen date. We would consequently expect the figures for the most recent few days to materially increase in future, and therefore the analysis below ignores the data for the most recent days, and ‘steps back’ by 4 days. This is designed to strike a balance between showing as up to date pictures as possible, and as accurate a picture as possible. However, we suspect some under-reporting remains in the most recent week used for the charts below.  

While the rolling seven-day average has continued to increase since last week, the rate of growth does appear to be slowing somewhat. The peak of the “second wave” in last week’s blog was on 7th October with 18,226 cases, whilst the peak in the above chart is 14th October with 19,635 cases – an increase of 1,409. However, the corresponding increase in last week’s blog was 5,101. While issues with reporting delays mentioned above mean that caution is required, it could be that we are starting to see some benefits from the tighter restrictions that have been brought in across many parts of the country.

Our “case-watch” for England

The graphic below compares this week’s “case-watch” to the previous week – with each point representing a (lower-tier) local authority2 in England. The best-case scenario would be for points to appear in the bottom left, indicating falling case numbers and suppression of the virus. If points appear to the right of the vertical line case numbers are rising – what we don’t want to see is points primarily to the right, and especially not heading towards the top right (high case numbers and rapidly growing) as this suggests the potential need to move away from localised restrictions to nationwide restrictions in order to “put the brakes on.”

The key change between the two weeks appears to be that there are now more local authorities who are seeing falls in new cases (the left hand side of the chart). The number of authorities on the left of the chart has increased from 9 to 105, and now covers around a third of the population of England, which is clearly welcome news.  

As we can see from the reduced vertical spread, there appears to be less variation from the national rate of cases. It is also worth noting that the overall level of new cases is growing, so the position on the y-axis is relative to that revised higher level. This is likely to mean that we see systemic growth in new cases across the country, instead of singular local outbreaks i.e. new virus transmissions are becoming much more of a national issue.

Focus on this week: The 3-tier system

In last week’s blog we discussed the new tiered system for local restrictions that had been brought in for England. The relevant restrictions of each tier are set out in detail on the government website, but in summary:

  • Medium: This is the baseline for restrictions, which were previously in place at the national level. This includes measures such as the ‘rule of 6’ and some hospitality restrictions after 10pm. We mark areas currently in the level with green dots in our chart below (although some are instead marked in red, representing areas which are causing us concern and may require a higher alert level in the near future).
  • High: This is for areas with higher weekly new case rates. It has been widely reported (but not officially confirmed) that the threshold for escalation from Medium to High alert level is over 100 new cases per 100,000 people. The greater restrictions include no household mixing in any indoor setting (light blue dots)
  • Very High: Highlighted as having a very high prevalence of COVID-19 requiring additional restrictions. Our understanding is that the exact restrictions imposed on any authorities in this category will be selected from a wide reaching menu (and, as we have seen with Greater Manchester, are subject to local negotiations around support packages), but as a minimum, local authorities are likely to see tighter restrictions on the hospitality sector, such as closing of pubs/bars, and bans on household mixing extended further to include outdoor areas. These are marked in lilac on our chart.

The list of areas in each region is published on the government website, and, as at 12pm on 22nd October, the in-force list currently names 100 local authorities in the High category (covering ~45% of England’s population) with the 20 local authorities that make up the Liverpool and Lancashire areas classified as Very High – the remaining local authorities are currently in the Medium classification. The 10 local authorities in the Greater Manchester area are moving to Very High from Friday (23rd) with the 4 local authorities in South Yorkshire moving to Very High on Saturday (24th).

Focus on this week: Which local authorities might be of emerging concern?

The Liverpool area was the first region to be placed in the Very High category. While Liverpool and surrounding areas (such as Knowsley) continue to have high new case rates compared to the national average (which is also high), encouragingly cases have fallen over the last week. It could be that the strengthened restrictions are beginning to have the desired impact. However, Blackpool and Blackburn with Darwen are in Lancashire, which was moved to Very High alert more recently, and continue to see high case rates and growth.

Given the controversy around moving Greater Manchester from High to Very High, it is interesting to note that in Manchester itself the number of new cases has again fallen compared to the previous week – suggesting that current restrictions may be starting to slow the virus transmission. Although nearby Bolton, also in Greater Manchester, has seen a large increase in cases over the last week.

The rise in cases seen in Barnsley and Doncaster also highlights why the decision was made to move South Yorkshire to the Very High alert level this weekend.

The “case-watch” chart above also marks a number of local authorities in red. These are areas currently classified as Medium risk, but which give cause for concern, either due to high case numbers or very high (and statistically significant) growth in the new case rate. Of these, the City of Bristol and Stoke on Trent show high increases in cases compared to their position last week, while Charnwood saw relatively high growth. They also exceed the 100 new cases weekly per 100,000 people threshold (represented by the yellow dotted line) which is believed to be one of the criteria for moving from Medium to High risk levels. Given that Bristol also saw a large rise in cases last week, local health authorities will be monitoring things closely.

In more positive news, 3 areas (Exeter, Newcastle upon Tyne and Nottingham) have seen such marked falls in case numbers over the past week that they are not shown on the chart as they are below the lower limit of the horizontal axis. Although both Newcastle upon Tyne and Nottingham are on the High alert level, and continue to have relatively high new case rates, they may be starting to turn a corner.

The national weekly new case rate for week ending 9th October was 162 per 100,000 people, well above the believed threshold for High alert status.  The weekly new case rate for the week ending 16th October was 172 per 100,000, a 6% increase over the previous week. This is significantly lower than the increase over the week before, and suggests that the rate of growth of the new case rate may be beginning to slow, which would be a welcome development.

All the local authorities categorised as Very High risk (lilac dots), and 79 of the 100 local authorities categorised as High risk (blue dots) have cases greater than 100 per 100,000. There are also 68 areas which are currently on Medium alert but sit above the yellow line. It will be interesting to watch developments in the next few weeks to see whether any of the regions of possible concern as well as those above the yellow line are moved to the High alert level.

As we were finalising this blog, it was announced that Stoke-on-Trent, along with Coventry and Slough, would move to the High alert level on Saturday (24th), while negotiations are ongoing around moving Warrington from High to Very High risk.

Case numbers in Wales

We have updated our analysis of the daily case data for Wales, as published by Public Health Wales, split by the 22 Local Authorities. While there is no Welsh equivalent of the 3-tier alert level now used in England, and a nationwide “firebreak” is being put in place this Friday, we nonetheless highlight in the chart below areas with existing local lockdowns/interventions, as well as those areas where new case numbers / growth in new cases is of concern. Note that as some areas have relatively small populations, the results can be quite volatile from week to week.

It is encouraging to see that cases are falling in 7 out of 22 areas (covering ~27% of the total population).

The local authorities are grouped close to the horizontal axis, which demonstrates why national level restrictions are coming into force.  However case numbers in Cardiff continue to rise, in particular in a number of areas with high student populations.

Overall, new case rates are similar in Wales to England – running at 172 per 100,000 lives in week to 16th October, up from 161 in the week before. 12 of the 25 local authorities in Wales fall above the 100 per 100,000 people weekly new case level, covering ~62% of the population.

Case numbers in Scotland

There are currently a range of restrictions on the hospitality industry in Scotland, with particularly tight restrictions across the central belt. These restrictions have been extended for another week. In the meantime, the Scottish Government is finalising plans to introduce a similar tiered alert system to that introduced in England, possibly with up to 5 tiers, which is expected to be put in place from 2nd November.

We have updated our analysis of the daily case data for Scotland, as published by Public Health Scotland, split by the 32 Council Areas.

Scotland has the lowest weekly new cases amongst the home nations. For the week up to 9th October (which determines level of x axis in the chart) there were 133 new cases per 100,000. For the week to 16th October this had increased to 154 per 1000,000, largely driven by continued case growth in the central belt.

We can see from the chart that:

  • While cases are rising across much of the country, 8 council authorities, covering around 23% of the population, have seen decreases since the previous week. In particular, the City of Edinburgh has seen a marked fall.
  • Of the 13 council authorities which have seen high cases, both compared to the previous week and the national average (i.e. the top right of the chart), all but one is in the central belt, illustrating why tighter restrictions have been put in place in these areas.
  • The one exception is Dundee, which again is showing cases greater than 100 per 100,000, although with a smaller increase in cases than we saw last time.
  • Neighbouring North Lanarkshire and South Lanarkshire have both seen strong growth in cases and have the highest case rates in Scotland. If this continues, they may be candidates for the highest tier under the new alert system when it is introduced next month.

Case numbers in Northern Ireland

Despite the Northern Ireland executive’s decision to implement a national ‘circuit-breaker’ lockdown, which has now been in place for almost two weeks, nearly every local government district has again seen increases in cases numbers (with the one exception being Newry, Mourne and Down).

The Derry City and Strabane area continues to have a high growth rate of cases, although the weekly increase is lower than in previous weeks. The case rate in the rest of the country is fairly consistent, emphasising the need for national restrictions. Mid Ulster has also seen a large increase in cases over the week.

Further, the weekly case rates in Northern Ireland are much higher, and growing faster, than those in the other home nations; rising from 293 per 100,000 people in the week to 8th October to 377 per 100,000 in the week to 15th October. We can see the scale of the problem by comparing the position of the ‘100 cases per 100,000’ line, which is well below the horizontal axis (which is fixed on the national rate).

If this situation continues, it may be that the ‘circuit break’ currently in place across Northern Ireland will need to be extended and/or further stronger restrictions will be needed to stem the surge in cases.


NOTES:

1. Pillar 1 and Pillar 2 testing – see our earlier blog which explain the Pillars.

2. For those familiar with the English local authority system these are “lower tier” local authorities – the smallest regional unit where data is readily (and publicly) available.

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