On the 11th December, we published a new report on our real-time tracking of the COVID-19 pandemic.
Here we have highlighted the latest findings and provided interpretation of what these findings mean. We have also explained our recent model and report changes.
- The current estimate of the daily number of new infections occurring each day across England is 58,800 (40,900–81,800, 95% credible interval).
- The daily number of new infections is particularly high in the Midlands regions (7,700 and 9,710 infections per day in the East and West, respectively), London (12,000) and the South-East (7,900). Note that a substantial proportion of these daily infections will be asymptomatic.
- We predict that the number of deaths occurring each day is likely to be between 305 and 531 on the 28th of December.
- We estimate Rt to be close to 1 in most regions. The probability of Rt exceeding 1 is above 80% in London, East of England (EE), South East (SE) and South West (SW), while it is less than 10% in the North East (NE). We can be certain that Rt is lower than 1 in Yorkshire and Humber (Y&H) and North West (NW).
- The growth rate for England is estimated to be 0.00 (-0.01–0.03, 95% credible interval) per day. This means that, nationally, the number of infections has stabilised. However, there is still evidence of continued growth in SE and SW, EE and London, while we confidently estimate we are beyond a second peak in infections in the NW, NE and Y&H.
- London, followed by the NW, continues to have the highest attack rate, that is the proportion of the population who have ever been infected, with 20% and 18% respectively. The SW continues to have the lowest attack rate though this has been revised upwards to 6%.
- 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.
The plots of Rt over time continue to show a downward trend, started in early-to-mid-September in the Northern regions and early-October elsewhere, resulting in values below 1 in NE, NW, YH and close to 1 in the West Midlands.
The number of new infections has peaked in the NE NW and YH and plateaued in the East and West Midlands, but continues to increase in the SE, SW, EE and London.
Trends in the number of daily deaths occurring each day follow a similar pattern but with a lag of 2-3 weeks. The combination of these different patterns across regions explain the unusual shape of the estimated trends for deaths.
The lower values of Rt and the decrease in the number of new infections are likely to be resulting from the combination of social distancing interventions, half-term school closures as well as the most recent lockdown. This lock-down seems to have contributed to the continuation of the downwards trends, however this contribution appears quite modest.
Additional comment from lead researcher – Professor Daniela De Angelis, MRC Investigator and Deputy Director
The different trends in the number of deaths and number of infections amongst the regions make interpretation of the current situation uncertain. The total number of new daily infections has been revised upward from our previous report to around 59,000. The volatility in this estimate primarily arises from these differing trends as well as the clustering of Rt values around 1. The estimated trends are likely to be the result of the complex interplay of the effects on transmission of the social restrictions introduced in October, the temporary decrease in activity over the half-term period, and the recent lockdown, though the impacts of the latter now appear to have been quite modest. The relative impacts of the lockdown compared to the new tiering measures cannot yet be estimated, and this makes any projections of how the pandemic will evolve in the run-up to Christmas highly uncertain. We will continue to monitor the situation closely.”
Model and report changes
- The definition of deaths has been adapted to include all deaths that occur in individuals who have had lab-confirmed infection within 60 days from the date of their most recent positive test. This definition reflects more realistically the burden of COVID-19.
- Using observations of improved survival in hospitalised COVID-19 patients, we have allowed the probability of dying following infection with SARS-CoV2 (the infection-fatality rate, IFR) to gradually change over the course of June 2020, with a decrease being estimated.
- The model uses seroprevalence data on the presence of COVID-19 antibodies in blood samples taken by NHSBT to estimate the levels of cumulative infection within the population over time. As of early June, the NHSBT has been giving a constantly declining prevalence of antibodies, and these data have been curtailed at this point.
- The modelling now accounts for a different susceptibility to infection in the under-15s, using information from literature (Viner et al, 2020) suggesting that children less likely to acquire infection when in contact with an infectious individual.
- The geographical definition has been changed from the seven NHS regions (here) to the nine regions typically used in government (here). This new spatial definition more appropriately reflects the existing regional heterogeneity.
Link to full report: https://www.mrc-bsu.cam.ac.uk/nowcasting-and-forecasting-11th-december-2020/