Predictive performance of multi-model ensemble forecasts of COVID-19 across European nations
Figures

Total number of forecasts included in evaluation, by target location, week ahead horizon, and variable.

Ensemble forecasts of weekly incident cases in Germany over periods of increasing SARS-CoV-2 variants Delta (B.1.617.2, left) and Omicron (B.1.1.529, right).
Black indicates observed data. Coloured ribbons represent each weekly forecast of 1–4 weeks ahead (showing median, 50%, and 90% probability). For each variant, forecasts are shown over an x-axis bounded by the earliest dates at which 5% and 99% of sequenced cases were identified as the respective variant of concern, while vertical dotted lines indicate the approximate date that the variant reached dominance (>50% sequenced cases).

Performance of short-term forecasts aggregated across all individually submitted models and the Hub ensemble, by horizon, forecasting cases (left) and deaths (right).
Performance measured by relative weighted interval score scaled against a baseline (dotted line, 1), and coverage of uncertainty at the 50% and 95% levels. Boxplot, with width proportional to number of observations, show interquartile ranges with outlying scores as faded points. The target range for each set of scores is shaded in yellow.

Performance of short-term forecasts across models and median ensemble (asterisk), by country, forecasting cases (top) and deaths (bottom) for 2-week ahead forecasts, according to the relative weighted interval score.
Boxplots show interquartile ranges, with outliers as faded points, and the ensemble model performance is marked by an asterisk. y-axis is cut-off to an upper bound of 4 for readability.
Tables
Predictive performance of main ensembles, as measured by the mean ratio of interval scores against the baseline ensemble.
Horizon | Weighted mean | Weighted median | Unweighted mean | Unweighted median |
---|---|---|---|---|
Cases | ||||
1 week | 0.63 | 0.64 | 0.61 | 0.64 |
2 weeks | 0.72 | 0.71 | 0.69 | 0.69 |
3 weeks | 0.82 | 0.76 | 0.82 | 0.72 |
4 weeks | 1.07 | 0.86 | 1.12 | 0.78 |
Deaths | ||||
1 week | 0.65 | 0.61 | 1.81 | 0.61 |
2 weeks | 0.58 | 0.54 | 1.29 | 0.54 |
3 weeks | 0.64 | 0.57 | 1.17 | 0.53 |
4 weeks | 0.82 | 0.67 | 0.84 | 0.62 |
Additional files
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Supplementary file 1
EPIFORGE reporting guidelines Completed checklist following reporting guidelines on epidemic forecasting research.
- https://cdn.elifesciences.org/articles/81916/elife-81916-supp1-v2.csv
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Supplementary file 2
Participating team metadata Team metadata for teams participating in the European Forecast Hub and evaluated in this study.
- https://cdn.elifesciences.org/articles/81916/elife-81916-supp2-v2.csv
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MDAR checklist
- https://cdn.elifesciences.org/articles/81916/elife-81916-mdarchecklist1-v2.pdf