Table 2.
Number and Percentage of Hospitalizations Averted Relative to the Number of Hospitalizations Without Vaccination
| Timing of the Vaccination Program Relative to the Start of Cases in the United States | No. of Hospitalizations Averted in High-Severitya (H) or Low-Severitya (L) Scenarios, % Hospitalizations Averted Relative to No Vaccine |
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|---|---|---|---|---|---|---|---|---|
| 10 Million Doses Administered per Week |
30 Million Doses Administered per Week |
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| Cumulative Clinical Attack Rate of 20% |
Cumulative Clinical Attack Rate of 30% |
Cumulative Clinical Attack Rate of 20% |
Cumulative Clinical Attack Rate of 30% |
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| 2009 H1N1-like Efficacyb | High Efficacyc | 2009 H1N1-like Efficacyb | High Efficacyc | 2009 H1N1-like Efficacyb | High Efficacyc | 2009 H1N1-like Efficacyc | High Efficacyc | |
| 16 wk before | 777 456 (H) | 1 105 624 (H) | 924 056 (H) | 1 362 815 (H) | 1 044 632 (H) | 1 417 695 (H) | 1 656 461 (H) | 2 252 778 (H) |
| 193 168 (L) | 274 706 (L) | 229 153 (L) | 338 608 (L) | 259 551 (L) | 352 243 (L) | 411 568 (L) | 559 730 (L) | |
| 29% | 41% | 21% | 32% | 39% | 53% | 38% | 52% | |
| 8 wk before | 567 650 (H) | 836 312 (H) | 569 629 (H) | 875 376 (H) | 1 039 148 (H) | 1 413 622 (H) | 1 441 707 (H) | 2 066 515 (H) |
| 141 040 (L) | 207 792 (L) | 141 531 (L) | 217 498 (L) | 258 189 (L) | 351 231 (L) | 358 209 (L) | 513 451 (L) | |
| 21% | 31% | 13% | 20% | 39% | 53% | 33% | 48% | |
| Same week as | 375 224 (H) | 572 394 (H) | 259 566 (H) | 448 871 (H) | 915 864 (H) | 1 303 629 (H) | 776 967 (H) | 1 326 099 (H) |
| 93 229 (L) | 142 218 (L) | 64 492 (L) | 111 527 (L) | 227 557 (L) | 323 902 (L) | 193 047 (L) | 329 485 (L) | |
| 14% | 21% | 6.0% | 10% | 34% | 48% | 18% | 31% | |
| 8 wk after | 183 325 (H) | 308 448 (H) | 12 132 (H) | 68 936 (H) | 537 550 (H) | 877 110 (H) | 36 394 (H) | 206 782 (H) |
| 45 549 (L) | 76 638 (L) | 3014 (L) | 17 128 (L) | 133 561 (L) | 217 929 (L) | 9043 (L) | 51 377 (L) | |
| 6.8% | 11% | 0.3% | 1.6% | 20% | 33% | 0.8% | 4.8% | |
| 16 wk after | 16 700 (H) | 52 206 (H) | 5 (H) | 79 (H) | 49 979 (H) | 156 030 (H) | 16 (H) | 236 (H) |
| 4149 (L) | 12 971 (L) | 1 (L) | 20 (L) | 12 418 (L) | 38 768 (L) | 4 (L) | 59 (L) | |
| 0.6% | 1.9% | 0% | 0% | 1.9% | 5.8% | 0% | 0% | |
Shown by number of vaccine doses administered per week (10 million or 30 million), cumulative clinical attack rate (20% vs 30%), clinical severity (high vs low), start of vaccination relative to cases (from 16 weeks before to 16 weeks after), and vaccine efficacy (moderate vs high).
a Overall case hospitalization ratio is 4.23% (high) or 1.05% (low).
b Two doses of vaccine administered 3 weeks apart required to be fully effective (62% for persons aged <60 years and 43% for persons ≥60 years) in protecting against subclinical and clinical cases, hospitalizations, and deaths. We assumed 1 dose of vaccine to be 0% effective for all age groups.
c Two doses of vaccine administered 3 weeks apart required to be to fully effective (80% for persons aged <60 years and 60% for persons ≥60 years) in protecting against subclinical and clinical cases, hospitalizations, and deaths. We assumed 1 dose of vaccine is 40% effective for persons aged <60 years and 30% for persons ≥60 years.