NIESR Weekly Covid-19 Tracker: Reproduction Number (R) and Forecasts of New Cases: R value for England increases slightly

Publication date: 15 Apr 2021 | Publication type: NIESR Covid-19 Tracker | NIESR Author(s): Thamotheram, C Issue 9

Main points

  • We report estimates of the R number and forecasts for new cases of Covid-19, hospital admissions, and deaths due to Covid-19 using data that was publicly available as on 13th April 2021.
  • SAGE has declared that due to the “increasing localised nature to managing the epidemic, particularly between nations” the UK wide estimate is less useful. To enable comparison with SAGE estimates we will henceforth produce estimates for England.  We will no longer be producing an R estimate for the UK as a whole.
  • Figure 1 shows that the Reproduction number, R, for England. R is the average number of secondary infections currently generated by an infected individual, estimated using the specimen date data until 9th April, increased to 0.80 – 0.95. As figure 2 shows, there has been a large reduction in Lateral Flow (LF) tests coinciding with the Easter vacation for Schools. We apply a correction to take account of this reduction. There has also been a change in reporting on 9th April to remove rapid LF tests that are confirmed as negative by a Polymerase Chain Reaction (PCR) test within 3 days. Thus, any change in testing by rapid LF tests has less of an effect on specimen cases than it previously would have done.
  • For Northern Ireland, the Reproduction number, R, is in the range is 0.95 – 1.10, for Wales 0.80 – 0.95 and for Scotland 0.75 – 0.90. The regional R number estimates given in Figure 6 show that, currently, the East Midlands has the lowest R number while London has the highest value across England’s regions.
  • Based on our model, by 17th may when stage 3 re-opening is due to restart, we expect the trend value of daily cases to be around 500; admissions to be around 100, and deaths to stay well below 50 (Figures 3-5).
  • To the extent that each stage of re-opening increases transmission, these numbers may increase. At the same time, expansion of the vaccination programme can be expected to reduce transmission. The trajectory that nets out these opposing trends could become evident in the weeks to come.

 

“Based on the latest data on new cases, our estimate of the R number for England lies in the range 0.80 – 0.95, up marginally from last week. This estimate is based on data up to 13th April 2021. If we do not apply the correction for the reduction in testing then the estimates would be slightly lower. This indicates that there has been some upward pressure on cases since the relaxation of the 29th March. Hospital admissions and deaths due to Covid-19 continue their steady decline.”

Dr Craig Thamotheram
Senior Economist - Macroeconomic Modelling and Forecasting

15th April 2021