Table 3.
Comparison of Vaccine Effectiveness Against Influenza A(H3N2) Estimated From Cox Proportional Hazards and Individual-Based Transmission Hazard Models, Household Influenza Vaccine Effectiveness Study, Ann Arbor, Michigan, 2010–2011
| Risk Group | No. of Infected Individuals | Total No. of Individuals | % | Cox Proportional Hazards Model | Individual-Based TH Model | ||
|---|---|---|---|---|---|---|---|
| VE, %a | 95% CI | VE, %a | 95% CrI | ||||
| Overall A(H3N2) | |||||||
| All Ages | 58 | 1,441 | 4.0 | 20.2 | −56.6, 59.4 | 27.3 | −23.0, 57.8 |
| <9 years of age | 32 | 468 | 6.8 | 39.9 | −49.1, 75.8 | 51.5 | 7.2, 75.2 |
| 9–17 years of age | 8 | 371 | 2.2 | −10.5 | −345.9, 72.6 | −30.1 | −617.7, 70.9 |
| ≥18 years of age | 18 | 602 | 3.0 | −13.2 | −187.5, 55.4 | −24.7 | −247.5, 52.7 |
| Community A(H3N2) | 41 | 1,441 | 2.8 | 15.8 | −65.4, 57.1 | 18.2 | −52.5, 55.8 |
| Household A(H3N2) | 17 | 111 | 15.3 | 49.5 | −41.3, 82.0 | 44.8 | −56.5, 80.2 |
Abbreviations: CI, confidence interval; CrI, credible interval; TH, transmission hazard; VE, vaccine effectiveness.
a VE was estimated via the hazard ratio in models that adjusted for age category (in years: <9, 9–17, ≥18) and presence of ≥1 high-risk health condition documented in the electronic medical record.