Table. Results From the Difference-in-Difference Model Assessing the Difference in the Estimated Number of Seasonal Influenza Cases in the 2019/2020 Season vs Previous 5 Seasons.
| Calendar week | Estimated No. of casesa | Difference-in-difference value in 2019/2020 vs 2014-2019 seasons (95% CI)a,b | |
|---|---|---|---|
| 2019/2020 season | 2014-2019 seasons | ||
| 40 | 71 | 10 | |
| 41 | 65 | 10 | |
| 42 | 52 | 13 | |
| 43 | 58 | 17 | |
| 44 | 69 | 22 | |
| 45 | 74 | 30 | |
| 46 | 133 | 44 | |
| 47 | 225 | 71 | |
| 48 | 402 | 117 | |
| 49 | 688 | 185 | |
| 50 | 1127 | 340 | |
| 51 | 1533 | 652 | |
| 52 | 1678 | 947 | |
| 1 | 1006 | 965 | –245 (–1535 to 1046) |
| 2 | 1322 | 1703 | –667 (–1957 to 624) |
| 3 | 1209 | 2634 | –1712 (–3002 to –421) |
| 4 | 1301 | 3048 | –2033 (–3324 to –743) |
| 5 | 1019 | 2883 | –2150 (–3440 to –859) |
| 6 | 654 | 2306 | –1937 (–3228 to –647) |
| 7 | 541 | 1668 | –1413 (–2704 to –123) |
| 8 | 447 | 1344 | –1182 (–2473 to 108) |
| 9 | 344 | 1129 | –1071 (–2361 to 220) |
| 10 | 227 | 864 | –923 (–2214 to 368) |
| 11 | 93 | 681 | –874 (–2164 to 417) |
a
Numbers are reported in thousands.
b
Subtraction of differences before week 1 from week 1 to 11 differences. Negative values represent fewer cases in the 2019/2020 season vs the 2014 to 2019 seasons. The difference-in-difference regression model included categorical variables for each week of the season and for the 2019/2020 season (vs previous seasons) and interaction variables between each of weeks 1 to 11 and the 2019/2020 season.