Table 2. Comparison of Primary and Alternative Models Estimating Public Health Impact of COVID-19 Vaccination in California.
| Age group by model, y | Observed outcome, No. | Estimated outcome, No. | Averted outcome, No. | Relative reduction in outcome, %a | |
|---|---|---|---|---|---|
| Unadjusted | Adjusted | ||||
| COVID-19 case | |||||
| Primary model | |||||
| ≥12 | 2 983 152 | 4 506 620 (95% PI, 3 959 910-5 213 980) | 1 523 500 (95% PI, 976 800-2 230 800) | 34 (95% PI, 25-43) | 72 (95% PI, 53-91) |
| 12-17 | 238 031 | 278 960 (95% PI, 268 300-290 120) | 40 930 (95% PI, 30 300-52 100) | 15 (95% PI, 11-18) | 57 (95% PI, 44-70) |
| 18-49 | 1 829 625 | 2 866 350 (95% PI, 2 444 720-3 412 980) | 1 036 700 (95% PI, 615 100-1 588 400) | 36 (95% PI, 25-46) | 83 (95% PI, 58-100) |
| 50-64 | 588 553 | 894 900 (95% PI, 810 040-1 003 720) | 306 300 (95% PI, 221 500-415 200) | 34 (95% PI, 27-41) | 66 (95% PI, 52-79) |
| ≥65 | 326 943 | 466 410 (95% PI, 436 850-507 170) | 139 500 (95% PI, 109 900-180 200) | 30 (95% PI, 25-36) | 49 (95% PI, 42-59) |
| Alternative model | |||||
| ≥12 | 2 983 152 | 4 385 300 (95% UI, 4 175 200-4 598 700) | 1 402 100 (95% UI, 1 192 100-1 615 600) | 32 (95% UI, 29-35) | 68 (95% UI, 61-75) |
| 12-17 | 238 031 | 316 790 (95% UI, 304 170-328 640) | 78 760 (95% UI, 66 140-90 610) | 25 (95% UI, 22-28) | 97 (95% UI, 85-100) |
| 18-49 | 1 829 625 | 2 640 320 (95% UI, 2 527 610-2 751 860) | 810 700 (95% UI, 697 990-922 240) | 31 (95% UI, 28-34) | 71 (95% UI, 64-77) |
| 50-64 | 588 553 | 909 830 (95% UI, 857 940-963 950) | 321 280 (95% UI, 269 390-375 390) | 35 (95% UI, 31-39) | 68 (95% UI, 60-75) |
| ≥65 | 326 943 | 518 340 (95% UI, 485 510-554 280) | 191 390 (95% UI, 158 570-227 340) | 37 (95% UI, 33-41) | 61 (95% UI, 54-68) |
| COVID-19 hospitalization | |||||
| Primary model | |||||
| ≥18 | 140 440 | 213 370 (95% PI, 193 690-239 590) | 72 930 (95% PI, 53 250-99 150) | 34 (95% PI, 27-41) | 70 (95% PI, 56-84) |
| 18-49 | 38 885 | 63 100 (95% PI, 54 410-74 540) | 24 220 (95% PI, 15 520-35 650) | 38 (95% PI, 29-48) | 88 (95% PI, 66-100) |
| 50-64 | 39 342 | 62 640 (95% PI, 56 940-69 960) | 23 300 (95% PI, 17 600-30 620) | 37 (95% PI, 31-44) | 71 95% PI, (59-84) |
| ≥65 | 62 213 | 87 630 (95% PI, 82 350-95 090) | 25 410 (95% PI, 20 140-32 880) | 29 (95% PI, 24-35) | 48 (95% PI, 40-57) |
| Alternative model | |||||
| ≥18 | 140 440 | 224 770 (95% UI, 212 200-237 950) | 84 330 (95% UI, 71 760-97 510) | 38 (95% UI, 34-41) | 76 (95% UI, 69-83) |
| 18-49 | 38 885 | 61 110 (95% UI, 58 270-63 910) | 22 230 (95% UI, 19 390-25 030) | 36 (95% UI, 33-39) | 84 (95% UI, 77-90) |
| 50-64 | 39 342 | 65 990 (95% UI, 62 000-70 140) | 26 650 (95% UI, 22 660-30 790) | 40 (95% UI, 37-44) | 77 (95% UI, 70-84) |
| ≥65 | 62 213 | 97 660 (95% UI, 91 930-103 900) | 35 450 (95% UI, 29 710-41 690) | 36 (95% UI, 32-40) | 60 (95% UI, 53-66) |
| COVID-19 death | |||||
| Primary model | |||||
| ≥18 | 45 060 | 64 490 (95% PI, 59 900-71 290) | 19 430 (95% PI, 14 840-26 230) | 30 (95% PI, 25-37) | 61 (95% PI, 50-75) |
| 18-49 | 3685 | 6420 (95% PI, 5560-7600) | 2730 (95% PI, 1880-3920) | 43 (95% PI, 34-52) | 98 (95% PI, 78-100) |
| 50-64 | 9803 | 15 870 (95% PI, 14 480,-17 720) | 6070 (95% PI, 4670-7920) | 38 (95% PI, 32-45) | 73 (95% PI, 62-86) |
| ≥65 | 31 572 | 42 200 (95% PI, 39 860-45 970) | 10 630 (95% PI, 8290-14 400) | 25 (95% PI, 21-31) | 42 (95% PI, 34-52) |
| Alternative model | |||||
| ≥18 | 45 060 | 67 680 (95% UI, 64 340-71 250) | 22 620 (95% UI, 19 280-26 190) | 33 (95% UI, 30-37) | 68 (95% UI, 61-75) |
| 18-49 | 3685 | 6100 (95% UI, 5810-6390) | 2410 (95% UI, 2130-2700) | 40 (95% UI, 37-42) | 91 (95% UI, 84-97) |
| 50-64 | 9803 | 16 290 (95% UI, 15 360-17 260) | 6490 (95% UI, 5560-7460) | 40 (95% UI, 36-43) | 76 (95% UI, 69-83) |
| ≥65 | 31 572 | 45 290 (95% UI, 43 170-47 590) | 13 720 (95% UI, 11 600-16 020) | 30 (95% UI, 27-34) | 50 (95% UI, 44-56) |
Abbreviations: PI, prediction interval; UI, uncertainty interval.
a
Relative reduction in outcomes were adjusted for the mean vaccine coverage in the population during the vaccine era, while the unadjusted estimate did not account for vaccine coverage.