COVID-19 short-term forecasts Confirmed 2020-06-27


Disclaimer

  • Forecasts produced by Jennie Castle, Jurgen Doornik, and David Hendry, researchers at the University of Oxford. These are our forecasts, and should not be considered official forecasts from, or endorsed by, any of: University of Oxford, Oxford Martin School, Nuffield College, or Magdalen College.
  • These forecasts are short term time-series extrapolations of the data. They are not based on epidemiological modelling or simulations. The documentation that is provided is still in progress and not peer reviewed. All forecasts are uncertain: their success can only be determined afterwards. Many mitigation strategies are in place, which, if successful, invalidate our forecasts. An explanation of our methods is provided below.

Recent changes

[2020-03-24] Our forecasts are starting to overestimate in some cases. This was always expected to happen when the increase starts to slow down. Scenario forecasts that are based on what happened in China earlier this year, but only for Italy and Spain sofar.
[2020-03-26] Scenario forecasts that are based on what happened in China earlier this year, only for Italy.
[2020-03-31] Scenario forecasts, based on what happened in China earlier this year, are presented for several countries (line marked with x). Created more plausible 90% confidence bands (dotted line in same colour).
[2020-04-02] Now including more US States, based on New York Times data. And the world.
[2020-04-06] Added a post hoc estimate of the peak number of cases. This needs at least three confirmed observations (four for deaths) after the event. It is based on the averaged smooth trend, and can change later or be a local peak. It is marked with a vertical line with the date label, or a date with left arrow in the bottom left corner of the graph. This is backported to 2020-04-04.
[2020-04-08] Minor correction to peak estimates. Added table with scenario forecasts.
[2020-04-09] Added table with estimated peak dates (if happened) and dates to and since the peak. Note that this can be a local peak, and subsequent re-acceleration (or data revisions) can result in a new peak later.
[2020-04-10] Updated documentation with better description of short-term estimates and peak determination.
[2020-04-16] Added scenario forecasts to all graphs now. This would now be the preferred forecast for most.
This is the first time with a peak in confirmed UK cases (also for deaths, but this is uncertain because it is at the same date).
[2020-04-17] Bird and Nielsen look into nowcasting death counts in England.
[2020-04-24] A summary of our work on short-term COVID-19 forecasting appeared as a voxeu.
[2020-04-27] Our short-term COVID-19 forecasting paper is now available as Nuffield Economics Discussion Paper 2020-W06.
A small adjustment has been made to the scenario forecast methodology, and will be documented shortly.
[2020-04-29] See our blog entry at the International Institute of Forecasters.
US history of death counts revised in Johns Hopkins/CSSE data.
UK death counts have been revised to include the deaths in care homes. In the Johns Hopkins/CSSE data set, which we use, the entire history has been revised. So forecasts made up to 2020-04-29 cannot be compared to later outcomes. In the ECDC data set only the last observation has changed, causing a jump in the series.
[2020-05-06] The New York Times is in the process of redefining its US state data. Unfortunately, at the moment only the last observation has changed (e.g New York deaths jumped from 19645 on 2020-05-05 to 25956 a day later). This means the data is currently useless; however it does bring it close to the Johns Hopkins/CSSE count (25626 on 2020-05-06). The aggregate US count is based on JH/CSSE so unaffected. We now use Johns Hopkins/CSSE US state data, including all states with sufficient counts. So the new forecasts cannot be compared to those previously.
A minor change is that we show the graph without scenario forecast if no peak has been detected yet.
[2020-05-13] We now omit countries with fewer than 200 confirmed cases in the last week (25 for deaths).
The short-term paper has some small updates, including further comparisons with other models.
Data for Ecuador are not reliable enough for forecasting.
Switched to an improved version of scenario forecasting.
[2020-05-18] Minor fixes to the improved version of scenario forecasting, backported to 2020-05-13.
[2020-05-20] Problem with UK confirmed cases: negative daily count. This makes the forecasts temporarily unreliable.
Updated the second paper.
[2020-06-04] Data issues with confirmed cases for France.
Added an appendix to the short term paper with further forecast comparisons for European and Latin American countries.
Both Sweden and Iran have lost their peak in confirmed cases. For Sweden the previous peak was on 24 April (daily peak of 656 cases), for Iran it was on 31 March (peak of 3116). For Iran this looks like a second wave, with increasing daily counts for the last four weeks. For Sweden this is a sudden jump in confirmed cases in the last two days, compared to a fairly steady weekly pattern over the previous six weeks.
[2020-06-06] Removed Brazil from yesterday's forecasts (only; last observation 2020-06-05).
[2020-06-24] Research presentation on short-term COVID-19 forecasting on 26 June (14:00 UK time) at the Quarterly Forecasting Forum of the IIF UK Chapter.

Further information

  • We believe these forecasts fill a useful gap in the short run. They give an indication of what is likely to happen in the next few days, removing some aspect of surprise. Moreover, a noticeable drop in comparison to the extrapolations could be an indication that the implemented policies are having some impact. It is difficult to understand exponential growth. We hope that these forecasts may help to convince viewers to adhere to the policies implemented by their respective governments, and keep all arguments factual and measured.
  • We use the data repository for the 2019 Novel Coronavirus Visual Dashboard operated by the Johns Hopkins University Center for Systems Science and Engineering. This is updated daily, but we tend to update our forecasts only every other day.
    US state data as of 2020-03-28 is courtesy of the New York Times.
  • We can only provide forecasts of what is measured. If confirmed cases are an underestimate of actual cases, then our forecasts will also be underestimates. No other epidemiological data is used. Data definition and collection differs between countries and may change over time.
  • We will update the methodology as we learn what is happening in the next few days or weeks. Once the number of cases levels off, there is no need to provide these forecasts anymore.
  • Countries where the counts are very low or stable have been omitted.
  • The graphs have dates on the horizontal axis (yyyy-mm-dd) and cumulative counts on the vertical axis. They show
    1. bold dark grey line (with circles): observed counts (Johns Hopkins CSSE);
    2. many light grey lines (with open circles): forecasts using different model settings and starting up to four periods back;
    3. red line (with open circles): single forecasts path using default model settings;
    4. black line (with crosses): average of all forecasts, recentered on the last observation;
    5. thin green lines: some indication of uncertainty around the red forecasts, but we do not know how reliable that is.
    Both the red line forecasts and the black lines are also given in the tables above. These forecasts differ, we are currently inclined to use the average forecasts.
  • The forecasts are constructed as follows:
    1. An overall `trend' is extracted by taking a window of the data at a time. In each window we draw `straight lines' which are selected using an automatic econometric procedure (`machine learning'). All straight lines are collected and averaged, giving the trend.
    2. Forecasts are made using the estimated trend, but we note that this must be done carefully, because simply extrapolating the flexible insample trend would lead to wildly fluctuating forecast. We use the `Cardt' method, which has been found to work well in other settings.
    3. Residuals from the trend are also forecast, and combined with trend forecasts into an overall forecast.
  • Scenario forecasts are constructed very differently: smooth versions of the Chinese experience are matched at different lag lengths with the path of each country. This probably works best from the peak, or the slowdown just before (but we include it for the UK nonetheless).
  • The forecast evaluation shows past forecasts, together with the outcomes (in the grey line with circles).
  • EU-BS is Estonia, Latvia, and Lithuania together.
  • This paper describes the methodology and gives further references. Also available as Nuffield Economics Discussion Paper 2020-W06. Still preliminary is the documentation of the medium term forecasts.

Confirmed count average forecast Latin America (bold black line in graphs) 2020-06-28 to 2020-07-04

DateArgentinaBoliviaBrazilChileColombiaCosta RicaDominican RepublicEcuadorEl SalvadorGuatemalaHaitiHondurasMexicoNicaraguaPanamaPeruVenezuela
2020-06-27 57744 30676 1313667 267766 84660 2979 30619 54574 5727 16397 5777 17007 212802 2170 30658 275989 5130
2020-06-28 60700 31900 1366000 270000 85700 3090 31500 54800 5930 17000 5820 17800 220000 2190 31600 278000 5220
2020-06-29 63800 33200 1426000 272000 87200 3240 32500 55300 6150 17600 5890 18600 228000 2230 32700 281000 5440
2020-06-30 67000 34600 1488000 275000 89300 3400 33500 55700 6380 18300 5980 19500 237000 2290 33800 284000 5670
2020-07-01 70400 36100 1553000 278000 91300 3560 34500 56200 6610 19000 6070 20500 246000 2340 34900 287000 5910
2020-07-02 74000 37600 1622000 281000 93500 3730 35600 56600 6860 19800 6160 21400 255000 2410 36100 290000 6160
2020-07-03 77800 39200 1693000 284000 95700 3900 36800 57200 7110 20500 6250 22500 265000 2470 37300 294000 6430
2020-07-04 81800 40900 1768000 287000 98000 4090 37900 57700 7370 21300 6340 23600 275000 2540 38500 297000 6700

Confirmed count forecast Latin America (bold red line in graphs) 2020-06-28 to 2020-07-04

DateArgentinaBoliviaBrazilChileColombiaCosta RicaDominican RepublicEcuadorEl SalvadorGuatemalaHaitiHondurasMexicoNicaraguaPanamaPeruVenezuela
2020-06-27 57744 30676 1313667 267766 84660 2979 30619 54574 5727 16397 5777 17007 212802 2170 30658 275989 5130
2020-06-28 60800 31900 1371000 271000 87000 3120 31500 55100 5950 17100 5870 17700 220000 2170 31700 279000 5320
2020-06-29 63800 33300 1431000 274000 90000 3260 32500 55700 6180 17900 5950 18600 227000 2170 32700 282000 5560
2020-06-30 66900 34700 1493000 277000 93000 3410 33400 56400 6420 18600 6040 19400 235000 2190 33800 285000 5820
2020-07-01 70200 36100 1559000 280000 96000 3560 34400 57000 6660 19300 6130 20300 243000 2210 35000 289000 6080
2020-07-02 73700 37600 1628000 282000 99000 3720 35500 57700 6920 20100 6220 21300 251000 2230 36200 292000 6350
2020-07-03 77300 39200 1700000 285000 102000 3880 36500 58300 7180 20900 6320 22200 260000 2260 37500 295000 6640
2020-07-04 81100 40900 1775000 288000 106000 4050 37600 59000 7460 21700 6410 23300 269000 2280 38800 298000 6940

Confirmed count scenario forecast (bold purple line in graphs) 2020-06-28 to 2020-07-06

DateArgentinaBoliviaBrazilChileColombiaCosta RicaDominican RepublicEcuadorEl SalvadorGuatemalaHaitiHondurasMexicoNicaraguaPanamaPeruVenezuela
2020-06-27 57744 30676 1313667 267766 84660 2979 30619 54574 5727 16397 5777 17007 212802 2170 30658 275989 5130
2020-06-28 60200 31600 1354000 270000 86500 3090 31200 54800 5880 16900 5820 17600 218000 2210 31400 278000 5260
2020-06-29 62200 32300 1386000 274000 88600 3220 31600 55300 6020 17400 5900 18200 222000 2240 32200 281000 5460
2020-06-30 64300 33000 1423000 278000 91000 3300 32000 55700 6130 17700 5950 18700 226000 2260 32700 283000 5620
2020-07-01 66300 33700 1452000 281000 92700 3370 32500 56000 6250 18100 6000 19400 229000 2270 33400 286000 5830
2020-07-02 68000 34200 1472000 283000 94200 3440 32700 56200 6430 18500 6070 20000 232000 2280 33900 288000 5990
2020-07-03 69500 34700 1501000 286000 95800 3530 33000 56400 6540 18900 6120 20700 235000 2280 34500 291000 6190
2020-07-04 71100 35200 1520000 290000 97100 3570 33300 56700 6650 19400 6170 21100 238000 2290 35000 293000 6320
2020-07-05 72500 35700 1539000 294000 98300 3620 33500 56800 6790 19700 6200 21600 240000 2300 35600 295000 6510
2020-07-06 73900 36200 1559000 295000 99600 3680 33900 56900 6890 20200 6240 22100 243000 2300 36000 297000 6700

Peak increase in estimated trend of Confirmed in Latin America 2020-06-27

ArgentinaBoliviaBrazilChileColombiaCosta RicaDominican RepublicEcuadorEl SalvadorGuatemalaHaitiHondurasMexicoNicaraguaPanamaPeruVenezuela
Peak date -- -- --06-17 -- -- --04-24 -- --06-07 -- --05-26 --05-31 --
Peak daily increment 15778 3836 205 119 6759
Days from 100 to peak 93 37 33 7 75
Days from peak/2 to peak 64 26 33 7 53
Last total 57744 30676 1313667 267766 84660 2979 30619 54574 5727 16397 5777 17007 212802 2170 30658 275989 5130
Last daily increment 2401 1253 38693 4406 3849 143 855 718 210 569 55 1013 4410 0 753 3625 351
Last week 14959 6288 230326 25411 15824 766 3942 3934 1101 3252 700 4238 32257 347 4628 21053 1213
Days since peak 10 64 20 32 27

Initial visual evaluation of forecasts of Confirmed