We have published a new report on our real-time tracking of COVID-19.
We have highlighted the key updates and provided interpretation of what these updates mean, and the lead researchers have also given their headline comment.
- The estimate of the daily number of new infections on the 15th October across England is 77,800 (68,200–88,000, 95% credible interval). The daily infection rate is estimated to be 139 per 100k population per day nationally. The highest rates are now the South West (SW) and the West Midlands (WM) with 192 and 190 infections per 100K population, corresponding to 10,800 and 11,200 daily infections respectively. These are closely followed by the East of England (EE) and Yorkshire and the Humber (YH)with 168 and 147 infections per 100k respectively. The North East (NE) and the East Midlands (EM) have daily infection rates around 135 per 100k, with only London (GL) having infection rates below 100 per 100k. Note that a substantial proportion of these infections will be asymptomatic.
- The number of deaths occurring daily is estimated to be increasing once again, such that we forecast between 112 and 180 deaths per day by the 5th of November.
- In many regions we now think it is likely that Rt is bigger than 1. The results show that the probability Rt > 1 is highest in the North West (NW) (84%) and is similarly high in EE and the South East (SE) (76% and 73% respectively), and just above 50% in the SW. However, it is also very low in some regions, GL, NE and EM in particular with probabilities of 11%, 8% and 2% respectively.
- The growth rate for England is estimated to be 0.00 (-0.01–0.01) per day. This means that, nationally, the number of infections is currently flat, corresponding to an Rt around 1.
- Our estimates for the attack rate, that is the proportion of the regional populations who have ever been infected, have been revised upwards with GL and NE highest at 58%. WM, NW and YH are all also above the national average with 54%, 52% and 49% respectively. The SE and SW continue to have the lowest attack rates at 35% and 33%.
- Note that the deaths data used are only very weakly informative on Rt over the last two weeks. Therefore, the estimate for current incidence, Rt and the forecast of daily numbers of deaths are likely to be subject to some revision.
Our estimates show a pandemic that is moving towards Rt = 1 following a sustained period of increasing infections since Sep 6th, the start of the autumn school term. This prolonged rise in the number of infections, initially in school-age children, is now only apparent among the >45yrs. The pandemic data that we use typically inform incidence up until about two weeks ago. At this time in almost all regions the probability that Rt is greater than 1 is in excess of 90%. At the current high levels of incidence we estimate a drop in Rt of around 0.2 over the following two weeks, bringing the Rt values close to 1.0.
The data on deaths within 60 days of a positive test show a recent peak having been gradually increasing since mid-June. Our model predicts a further increase over the coming three weeks, although the actual numbers will still remain low in comparison to the peaks of the first two waves of infection.
Plots of the IFR over time show that from the end of January we estimate a decreasing IFR in all adult age groups, but most steeply in the older ages. This drop indicates the benefits of immunisation against death over and above the benefits against infection. Following this drop, there has been a period of plateau followed by a slight increase to 3.0% (2.8%–3.1%) in the over-75s and 0.20% (0.19%–0.20%) overall.
For context, in addition to the data used here, the numbers of reported new positive tests (by date of specimen) have been steadily increasing since the second week of September. These case numbers are, however, highly dependent on the volume and targeting of testing, the public’s testing behaviour and might be subject to significant reporting delay, and therefore are difficult to interpret. Hospital admission show slow growth from the third week of September, slightly lagging behind the cases while the prevalence of infection, as estimated by the ONS Coronavirus Infections Survey, has risen consistently over the last four weeks to 1.6% in England, the highest level it has been since early January, 2021.
Headline comment from lead researchers, Prof Daniela De Angelis and Dr Paul Birrell
Our results show signs of a persistent epidemic with a national infection at around 140 per 100,000 population. Underlying this is an increase in infections over the last month from 49,000 on 6th September, to 78,000 by the 8th October. Initially in the school age children after the school re-opening, this rise is now concerningly becoming apparent in those aged 45+. Levels of hospital admissions are showing an increase and deaths also on the rise after a temporary plateau. There has also been an increase in the ONS survey’s estimate of overall prevalence, particularly in school-age groups. This suggests a fluid situation, which we will continue to monitor carefully.
Model and report changes
- The model now accounts for the ongoing immunisation programme, stratifying the population of people still susceptible to infection with the virus according to their immunisation status (unimmunised/1 dose/2 doses). We use data on the daily proportions of the population getting immunised to inform this splitting of the population, assuming that it takes three weeks for vaccine-derived immunity to develop. Vaccine efficacy is assumed against both infection and death, using values for the efficacy in agreement with those found here. We have a changepoint in the vaccine efficacy on the 10th May, which marks a transition from alpha being the dominant variant, to delta.
- The model also accounts for a different susceptibility to infection in each adult age group (no prior information is used); and for the under-15s, (using prior information from Viner et al, 2020, which estimates children to be less likely to acquire infection when in contact with an infectious individual).
- The model has the ability to incorporate estimates of community prevalence, by region and age group, from the Office of National Statistics COVID-19 Infection Survey (see Data Sources for details). These are included weekly since the outset of the Survey in May 2020 for the age groups >4 years to inform trends in incidence that are too recent to be captured by the data on deaths.
- We have extended the use of serological sampling data to use samples taken beyond the first wave of the pandemic. The samples are those collected by NHS Blood and Transplant using the Roche-N assay, which measures the prevalence of infection-acquired antibodies in the population.
- The underlying probability of an unvaccinated individual dying following infection with SARS-CoV2 (the infection-fatality rate, IFR) is allowed to change gradually over the course of 30 days every (approximately) 100 days. This is designed to reflect fluctuations due to seasonal effects, demand on healthcare services or the emergence of new virus variants of differing severity.
- The ‘Epidemic summary’ only reports the current value for the IFR by age. To visualise how this has changed over time in our model, see the IFR tab in the ‘Infections and Deaths’ section of the report. The quantity that is now plotted under this tab is the probability of dying if infected, taking into account the impact of the immunisation programme – it is an average of a lower rate of death in vaccinated individuals and a higher rate among the unvaccinated.