NIESR Weekly Covid-19 Tracker: Reproduction Number (R) and Forecasts of New Cases: Daily cases to rise slightly

Publication date: 13 May 2021 | Publication type: NIESR Covid-19 Tracker | NIESR Author(s): Thamotheram, C Issue 13

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 of 11th May 2021.
  • Figure 1 shows that the Reproduction number, R, for England. R is the average number of secondary infections currently generated by an infected individual, and is estimated to be in the range of 0.95 – 1.10 based on specimen date data until 7th May.
  • This is to be seen in the context of 7-day case rates (calculated as the count of cases over the last 7 days divided by population multiplied by 100,000) in all nations and regions being less than 50 per 100.000. From this low base small changes in case numbers can have large effects on growth rates of new cases. As R is calculated directly as a function of growth rates of new cases (see Harvey and Kattuman (2020b)) this can give a misleading picture if the Reproduction number, R, is considered in isolation. We add the 7-day case rates to Figure 5 to draw attention to this.
  • For Northern Ireland the R number is in the range 0.90 – 1.05 (7-day case rate per 100, 000 of 31); for Wales, 0.95 – 1.10 (case rate of 7) and for Scotland, 1.00 – 1.15 (case rate of 23). The regional R number estimates and case rates given in Figure 5 show that, currently, the West Midlands (case rate of 17) has the lowest R number while the East Midlands (case rate of 29) has the highest value across England’s regions.
  • Based on our model, by 17th May when step 3 re-opening is due to restart, we expect the trend value of daily cases to be around 1,800; admissions to be below 100, and deaths to be well below 25 (Figures 3-5).

“It is reassuring that the weekly case rate per 100,000 is smaller than 50 in all regions and nations. Based on the latest data on new cases, our estimate of the R number for England lies in the range 0.95 – 1.10, increasing from last week. This estimate is based on data up to 11th May 2021, four weeks beyond step 2 of the roadmap out of lockdown and one week before step 3 reopening. This is the first time since early January when we forecast daily reported cases to rise, albeit mildly. Hospital admissions and deaths due to Covid-19 continue their steady decline.”

Dr Craig Thamotheram
Senior Economist - Macroeconomic Modelling and Forecasting

 

Please find the full analysis in the document attached