TABLE 2.
Unadjusted and adjusted hazard ratios and vaccine effectiveness estimates of COVID-19 vaccines (BNT162b2, mRNA-1273, and ChAdOx1 nCoV-19) against laboratory-confirmed SARS-CoV-2 infection and clinically important outcomes (hospitalization or death) between December 14, 2020, and November 28, 2021, in solid organ transplant recipients from Ontario, Canada
| Rate per 100000 person-days | Unadjusted hazard ratio (95% CI) | Adjusted hazard ratioa (95% CI) | Unadjusted vaccine effectivenessb % (95% CI) | Adjusted vaccine effectivenessa,b % (95% CI) | |
|---|---|---|---|---|---|
| SARS-CoV-2 Infectionc | |||||
| Unvaccinated | 17.7 | Reference | Reference | Reference | Reference |
| One vaccine dose | 11.2 | 0.67 (0.47, 0.95) | 0.69 (0.49, 0.98) | 33 (5, 53) | 31 (2, 51) |
| Two vaccine doses | 4.8 | 0.55 (0.38, 0.81) | 0.54 (0.37, 0.79) | 45 (19, 62) | 46 (21, 63) |
| Three vaccine doses | 3.5 | 0.24 (0.12, 0.48) | 0.28 (0.14, 0.57) | 76 (52, 88) | 72 (43, 86) |
| Clinically important outcomes (composite of hospitalization or death)c | |||||
| Unvaccinated | 9.3 | Reference | Reference | Reference | Reference |
| One vaccine dose | 6.9 | 0.69 (0.44, 1.08) | 0.62 (0.39, 0.96) | 31 (−8, 56) | 38 (4, 61) |
| Two vaccine doses | 2.3 | 0.57 (0.34, 0.96) | 0.46 (0.27, 0.77) | 43 (4, 67) | 54 (23, 73) |
| Three vaccine doses | 2.0 | 0.37 (0.14, 0.97) | 0.33 (0.13, 0.89) | 63 (3, 86) | 67 (11, 87) |
Abbreviation: CI, confidence interval.
Model was adjusted for age, sex, public health unit region, number of SARS-CoV-2 tests in the 3 months prior to December 14, 2020 (0,1, ≥2), influenza vaccine in the 2019/20 or 2020/21 influenza season, solid organ transplant type (i.e., kidney, liver, lung, heart, pancreas, or multi-organ transplant), diabetes, chronic heart disease, major cancer, hypertension, chronic respiratory disease, SARS-CoV-2 infection in 90+ days prior to cohort entry (i.e., December 14, 2020), living in a long-term care residence, years since most recent transplant and several neighborhood-level variables (income [measured as quintiles], proportion of people working as a non-health essential worker [ranked into quintiles], persons per dwelling quintile, and self-identified visible minority quintiles).
Vaccine effectiveness was calculated using the formula: (1 – hazard ratio) × 100.
Vaccine categories: one vaccine dose: 14+ days after dose 1 until 13 days after dose 2; two vaccine doses: 14+ days after dose 2 until 13 days after dose 3; three vaccine doses: 14+ days after dose 3.