Nearly all regions in England have seen an increase in COVID-19 infection rates since the end of the national lockdown with numbers in London rising by nearly 75%, according to a brand-new analysis tracker from consultancy and analytics firm Lane Clark & Peacock (LCP), which provides an up-to-date estimate of the true prevalence of the virus.

The LCP Covid-19 Tracker uses an established actuarial method to integrate and analyse both the daily Public Health England (PHE) testing figures as well as the weekly Office for National Statistics (ONS) sample to give a more rounded picture of current infection rates which is vital to inform both national and local measures.

The tracker shows that the number of new cases declined substantially during the national four-week ‘lockdown’ period of November with new daily cases declining by around 31% from approximately 29,600 cases per day on 4 November to approximately 20,500 daily cases by 2 December. However, this decline appears to have plateaued with clear evidence of an increase in infections in many areas over the past week with new estimates of approximately 27,400 cases per day by Friday, 11 December.

This national picture also masks the large variations in trends and case numbers across the regions.  Those regions with the highest case rates at the beginning of the lockdown, such as the North West and Yorkshire and Humber, saw the largest declines during this November. For example, new daily cases declined by as much as 54% in the North West from 92 to 42 new cases per 100,000 per day during that period. However, these declines appeared to have stopped since the national restrictions finished on 2 December with Yorkshire and Humber the only region to have not seen cases increase since.

In contrast, areas with lower levels of cases going into the lockdown, such as London and the South East, saw slight increases during the lockdown period. Worryingly this trend has continued since the lockdown lifted with estimated increases of approximately 73% and 51% in these two regions, from 45 to 79 and 39 to 59 cases per 100,000 per day, respectively.

Ahead of the Government’s planned review of tiers on Wednesday, 16 December, the LCP tracker estimates that London became the region with highest Covid-19 incidence on 1 December. Specifically, estimated daily rates have increased by around 70% (from 45 per 100,000 to 79 per 100,000 in London) between 2 to 11 December with the East of England seeing similarly large estimated increases from 28 to 47 new cases per 100,000.

Commenting, Dr Jonathan Pearson-Stuttard, Head of LCP’s Health Analytics team, said: “This data provides an up-to-date estimate of infection rates in England. It suggests that national restrictions were most effective in areas where Covid-19 rates were highest and had been under more restrictive measures going into the national lockdown. Trends in areas such as London, South East and the East of England over the past week are concerning. This is particularly worrying in the run up to Christmas where increased social mixing is highly likely to lead to a rise in cases and hospitalisations in January putting further pressure on the NHS.”

Data Sources for the LCP Covid-19 tracker

Currently there are two main sources of official case estimates. The daily PHE Covid-19 testing data released on the UK Government dashboard reflects the number of positive results in those who have requested a test due to having symptoms. Data is often incomplete and revised upwards as days pass. This leads to the concept of a time-lag between the date of a Covid-19 test being taken by an individual (specimen date) and the date that the result of that test is recorded (date reported).

The ONS Covid-19 infection survey tests a random sample of the population to estimate closer to the true prevalence of infection in the community. This data is usually published weekly with a time lag of between six and 12 days.

Methodology - LCP Covid-19 tracker

The LCP Covid-19 tracker combines these two data sources to provide a more up-to-date  estimate of current incidence and prevalence of the virus by region across England.

It projects each day of PHE Covid-19 testing data upwards to give current estimated incidence rates, taking account of:

• the observed pattern of past time-lags between the specimen date and the reporting date; and
• observed differences between past PHE testing data and ONS surveillance data.

The tracker then standardises these infection rates to regional ONS populations for those aged 2 and over to estimate the total number of new daily cases per 100,000 people.  A similar method is used to estimate current case prevalence rates.

LCP Covid-19 estimates

The tracker projects each day of PHE Covid-19 testing data upwards to give current estimated incidence rates, taking account of:

• the observed pattern of past time-lags between the specimen date and the reporting date; and
• observed differences between past PHE testing data and ONS surveillance data.

It then standardises these infection rates to regional ONS populations for those aged 2 and over to estimate the total number of new daily cases per 100,000 people.  A similar method is used to estimate current case prevalence rates.