Table 3.
Observed and predicted influenza-like illness incidence under the counterfactual scenario
| Before COVID-19 | After COVID-19 | |||||||
|---|---|---|---|---|---|---|---|---|
| 2014–2019 | 2019–2020 (2019 W36 ~ 2020 W4) |
2020 (2020 W51 ~ 2020 W52) |
2021 | |||||
| Observeda | Observed | Observed | Predictedb | % Change | Observed | Predicted | % Change | |
| ILI total | 13.91 | 16.11 | 3.45 | 12.22 | -71.80 | 1.90 | 14.78 | -87.12 |
| Positive rate of IFV (%) | 12.92 | 14.03 | 1.68 | 10.09 | -73.94 | 0.0014 | 11.93 | -99.99 |
| Positive rate of IFV A (%) | 7.60 | 7.21 | 1.47 | 5.63 | -83.33 | 0.0014 | 6.95 | -99.98 |
2014–2019: week 36 of 2014 to week 35 of 2019
2019: week 1 of 2019 to week 52 of 2019
2020: week 5 of 2020 to week 52 of 2020
Week 5 of 2020: The first week after COVID-19 emergence
2021: week 1 of 2021 to week 52 of 2021
Percentage change = 100 × (observed- predicted)/predicted
IFV Influenza virus, IFV A Influenza virus A (H1N1/pdm09 and H3N2)
aObserved value is the average value of the base period
bPredicted under the counterfactual scenario (no non-pharmaceutical intervention)