COVID-19: nowcast and forecast

Summary

Real-time tracking of a pandemic, as data accumulate over time, is an essential component of a public health response to a new outbreak. This document reports the work of a joint Public Health England (PHE)—University of Cambridge modelling group to nowcast and forecast COVID-19 infections and deaths, together with estimation of relevant epidemiological quantities for England (by NHS region) and Scotland. These estimates have provided the bases of forecasts supplied to the Scientific Pandemic Influenza sub-group on Modelling (SPI-M) and to regional PHE teams.

Data Sources

We have been using data from the PHE-generated line-listing, as published on 06 May. This consists of a combination of deaths notified to:

• the Demographics Batch Service (DBS), a mechanism that allows PHE to submit a file of patient information to the National Health Service spine for tracing against the personal demographics service (PDS). PHE submit a line list of patients diagnoses with COVID-19 to DBS daily. The file is returned with a death flag and date of death updated (started 20^th March, 2020).
• NHS England, who report data from NHS trusts relating to patients who have died after admission to hospital or within emergency department settings.
• Health Protection Teams (HPTs), resulting from a select survey created by PHE to capture deaths occurring outside of hospital settings, e.g. care homes (started 23^rd March, 2020).

This covers all deaths where the fatality had a confirmed positive test. Deaths which have COVID-19 on the death certificate are included in ONS figures but not here; we are looking into their inclusion.

We have separately analysed the data by:

• date of death and by date of report (see Methods section)
• based on daily updates
• stratified into eight age groups: <1, 1-4, 5-14, 15-24, 25-44, 45-64, 65-74, 75+.
• stratified into NHS England regions (North East and Yorkshire, North West, Midlands, East of England, London, South East, South West) and Scotland.

Key values

Current R

Value of \(R_e\), the average number of secondary infections due to a typical infection today.

Attack rate

The percentage of a given group that has been infected.

By region

By age

IFR

Change in infections incidence

Growth rates

NB: negative growth rates are decline rates. Values are daily changes.

Region	Median	95% CrI (lower)	95% CrI (upper)
East of England	-0.07	-0.08	-0.06
London	-0.19	-0.21	-0.17
Midlands	-0.08	-0.09	-0.07
North East and Yorkshire	-0.04	-0.05	-0.04
North West	-0.06	-0.07	-0.05
South East	-0.07	-0.08	-0.06
South West	-0.05	-0.06	-0.04

Halving times

Halving times in days, if a region shows growth than value will be Inf.

Region	Median	95% CrI (lower)	95% CrI (upper)
East of England	10.06	8.70	11.79
London	3.36	2.95	3.78
Midlands	8.47	7.56	9.50
North East and Yorkshire	15.47	13.02	18.50
North West	11.07	9.58	12.79
South East	9.99	8.69	11.58
South West	13.31	10.65	17.11

Change in deaths incidence

Growth rates

NB: negative growth rates are decline rates. Values are daily changes.

Region	Median	95% CrI (lower)	95% CrI (upper)
East of England	-0.05	-0.06	-0.04
London	-0.09	-0.09	-0.09
Midlands	-0.06	-0.06	-0.05
North East and Yorkshire	-0.03	-0.04	-0.03
North West	-0.04	-0.05	-0.04
South East	-0.05	-0.06	-0.05
South West	-0.04	-0.05	-0.03

Halving times

Halving times in days, if a region shows growth than value will be Inf.

Region	Median	95% CrI (lower)	95% CrI (upper)
East of England	13.40	11.91	15.38
London	7.39	7.22	7.58
Midlands	11.58	10.68	12.64
North East and Yorkshire	20.93	17.73	25.34
North West	15.11	13.42	17.23
South East	13.04	11.71	14.82
South West	16.31	13.41	20.72

Infections and deaths

Blue line is date of lockdown (23 Mar), the red line is the date of results (06 May).

Infection incidence

By region

By age

Cumulative infections

By region

By age

Deaths incidence

By region

By age

Cumulative deaths

By region

By age

Rt