COVID-19 short-term forecasts Confirmed 2020-07-01 Latin American Countries


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 The documentation that is provided is still in progress and not peer reviewed.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.
[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.
[2020-06-29] Tables in April included the world, but not the world as we know it (double counting China and the US). So removed the world from those old tables.
Why short-term forecasts can be better than models for predicting how pandemics evolve just appeared at The Conversation.
Thursday 2 July webinar at the FGV EESP - São Paolo School of Economics. This starts at 16:00 UK time (UTC+01:00) and streamed here.
[2020-07-01] Modified the short-term model to allow for (slowly changing) seasonality. Many countries show clear seasonality after the initial period, likely caused by institutional factors regarding data collection. This seasonality was also getting in the way of peak detection. As a consequence estimates of the peak date may have changed for countries with strong seasonality.
Added forecasts of cumulative confirmed cases for lower tier local authorities of England. The data is available from 2020-07-02 including all tests (pillar one and two). Only authorities with more than 5 cases in the previous week are included.

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) 2020-07-02 to 2020-07-08

DateArgentinaBoliviaBrazilChileColombiaCosta RicaDominican RepublicEcuadorEl SalvadorGuatemalaHaitiHondurasMexicoNicaraguaPanamaParaguayPeruVenezuela
2020-07-01 67197 34227 1448753 282043 98090 3753 33387 58257 6736 19011 6040 20262 231770 2519 34463 2260 288477 6062
2020-07-02 70120 35440 1470000 285200 100500 3817 33950 58330 6931 19250 6100 21090 235700 2540 35050 2318 291300 6237
2020-07-03 73450 36840 1514000 289500 103900 3980 34580 58550 7190 19770 6175 22040 240500 2549 35860 2429 294400 6448
2020-07-04 76930 38340 1548000 293900 107500 4161 35240 59050 7485 20350 6256 23030 245500 2564 36730 2555 297500 6718
2020-07-05 80580 39860 1575000 298400 112000 4348 35910 59680 7788 20940 6341 24040 250500 2577 37740 2666 300700 6967
2020-07-06 84410 41470 1595000 302900 115400 4543 36520 60330 8058 21540 6433 25100 255200 2586 38720 2755 303800 7238
2020-07-07 88430 43150 1633000 307500 118900 4745 37190 60970 8373 22170 6528 26210 260400 2858 39510 2842 307000 7503
2020-07-08 92640 44930 1678000 312200 122400 4956 37890 61620 8707 22810 6626 27360 265800 2858 40370 2934 310300 7785

Confirmed count forecast Latin America (bold red line in graphs) 2020-07-02 to 2020-07-08

DateArgentinaBoliviaBrazilChileColombiaCosta RicaDominican RepublicEcuadorEl SalvadorGuatemalaHaitiHondurasMexicoNicaraguaPanamaParaguayPeruVenezuela
2020-07-01 67197 34227 1448753 282043 98090 3753 33387 58257 6736 19011 6040 20262 231770 2519 34463 2260 288477 6062
2020-07-02 70270 35720 1460000 286100 100900 3947 34060 58630 6988 19530 6134 21050 236700 2586 34710 2318 290800 6354
2020-07-03 73530 37310 1506000 290200 103700 4139 34700 59140 7254 20040 6228 21840 241400 2614 35580 2377 293100 6652
2020-07-04 76870 38890 1540000 294300 106400 4338 35490 59720 7539 20570 6319 22640 246200 2644 36400 2433 295500 6961
2020-07-05 80400 40580 1570000 298400 109000 4536 36300 60300 7838 21090 6413 23440 250900 2691 37360 2490 297800 7278
2020-07-06 84100 42350 1592000 302600 111700 4742 36600 60880 8151 21610 6507 24260 255600 2761 38360 2548 300200 7611
2020-07-07 87960 44210 1628000 306800 114500 4956 37240 61470 8479 22130 6601 25090 260400 3075 39080 2607 302600 7958
2020-07-08 92010 46170 1670000 311000 117200 5179 37980 62070 8822 22670 6696 25940 265200 3075 39880 2668 305000 8322

Confirmed count scenario forecast (bold purple line in graphs) 2020-07-02 to 2020-07-10

DateArgentinaBoliviaBrazilChileColombiaCosta RicaDominican RepublicEcuadorEl SalvadorGuatemalaHaitiHondurasMexicoNicaraguaPanamaParaguayPeruVenezuela
2020-07-01 67197 34227 1448753 282043 98090 3753 33387 58257 6736 19011 6040 20262 231770 2519 34463 2260 288477 6062
2020-07-02 69420 35220 1465000 285400 101100 3793 34080 58260 6920 19120 6126 21140 235700 2548 35090 2399 291000 6142
2020-07-03 72310 36520 1491000 289200 104200 4002 34770 58310 7133 19710 6198 22020 240100 2578 35840 2532 293400 6420
2020-07-04 74610 37170 1513000 291800 107300 4168 35380 58640 7307 20190 6249 22870 243900 2607 36420 2617 295800 6569
2020-07-05 75480 37740 1534000 293700 109900 4274 35930 58770 7451 20540 6303 23340 248300 2643 37060 2709 297700 6691
2020-07-06 76930 38180 1552000 295800 112600 4362 36400 59030 7614 20780 6352 24100 251700 2672 37680 2795 299100 6865
2020-07-07 78010 38690 1579000 296600 115000 4523 36730 59190 7777 21090 6394 24960 254600 2706 38190 2893 300300 6959
2020-07-08 79600 39240 1598000 297200 117400 4608 37130 59470 7942 21390 6440 25390 257800 2760 38980 2994 301400 7078
2020-07-09 81040 39830 1619000 297800 119600 4728 37560 59470 8065 21670 6483 26150 261000 2801 39650 3120 302400 7185
2020-07-10 82590 40290 1646000 299400 121500 4886 38040 59470 8156 21960 6516 27110 265600 2835 40130 3183 303600 7277

Peak increase in estimated trend of Confirmed in Latin America 2020-07-01

ArgentinaBoliviaBrazilChileColombiaCosta RicaDominican RepublicEcuadorEl SalvadorGuatemalaHaitiHondurasMexicoNicaraguaPanamaParaguayPeruVenezuela
Peak date -- -- --06-17 -- -- --04-24 -- --05-3106-2806-25 --06-2706-2805-30 --
Peak daily increment 32089 7779 177 915 5300 893 146 6110
Days from 100 to peak 93 38 25 91 100 100 84 72
Days from peak/2 to peak 48 18 26 71 79 94 88 53
Last total 67197 34227 1448753 282043 98090 3753 33387 58257 6736 19011 6040 20262 231770 2519 34463 2260 288477 6062
Last daily increment 2667 1008 46712 2650 2821 294 819 1825 298 915 65 704 5681 0 913 39 3264 230
Last week 14740 5724 220639 22979 20777 1069 4246 5101 1400 3392 497 4896 28819 349 5426 691 19875 1499
Days since peak 14 68 31 3 6 4 3 32

Initial visual evaluation of forecasts of Confirmed