Table 3. Effectiveness of Vaxzevriaa vaccine and Comirnatyb vaccine in preventing confirmed SARS-CoV-2 infection and infection outcomes, Navarre, Spain, January–April 2021 (n = 20,905)c .
| Evaluated outcome and vaccination status | Infections/contacts | Crude RR (95% CI) | Adjusted RR (95% CI)d | Adjusted VE % (95% CI)d |
|---|---|---|---|---|
| Confirmed SARS-CoV-2 infection e | ||||
| Unvaccinated | 6,980/19,580 | Reference | Reference | Reference |
| Vaxzevria with 1 dose | 99/524 | 0.53 (0.44 to 0.65) | 0.56 (0.46 to 0.69) | 44 (31 to 54) |
| Comirnaty with 1 dose | 90/310 | 0.81 (0.66 to 1.00) | 0.79 (0.64 to 0.97) | 21 (3 to 36) |
| Comirnaty with 2 doses | 61/491 | 0.35 (0.27 to 0.45) | 0.35 (0.27 to 0.44) | 65 (56 to 73) |
| Relative effect of 2 vs 1 dose of Comirnaty | 61/491 vs 90/310 | 0.43 (0.31 to 0.59) | 0.44 (0.32 to 0.61) | 56 (39 to 68) |
| Symptomatic COVID-19 | ||||
| Unvaccinated | 5,306/19,580 | Reference | Reference | Reference |
| Vaxzevria with 1 dose | 67/524 | 0.47 (0.37 to 0.60) | 0.50 (0.39 to 0.63) | 50 (37 to 61) |
| Comirnaty with 1 dose | 62/310 | 0.74 (0.58 to 0.95) | 0.70 (0.55 to 0.90) | 30 (10 to 45) |
| Comirnaty with 2 doses | 25/491 | 0.19 (0.13 to 0.28) | 0.18 (0.12 to 0.27) | 82 (73 to 88) |
| Relative effect of 2 vs 1 dose of Comirnaty | 25/491 vs 62/310 | 0.26 (0.16 to 0.41) | 0.26 (0.16 to 0.41) | 74 (59 to 84) |
| Hospitalisation due to COVID-19 | ||||
| Unvaccinated | 548/19,580 | Reference | Reference | Reference |
| Vaxzevria with 1 dose | 1/524 | 0.07 (0.01 to 0.49) | 0.08 (0.01 to 0.54) | 92 (46 to 99) |
| Comirnaty with 1 dose | 7/310 | 0.80 (0.38 to 1.70) | 0.35 (0.17 to 0.75) | 65 (25 to 83) |
| Comirnaty with 2 doses | 1/491 | 0.07 (0.01 to 0.52) | 0.06 (0.01 to 0.40) | 94 (60 to 99) |
| Relative effect of 2 vs 1 dose of Comirnaty | 1/491 vs 7/310 | 0.09 (0.01 to 0.73) | 0.16 (0.02 to 1.29) | 84 (–29 to 98) |
| Symptomatic COVID-19 in 18 to 59 year age group | ||||
| Unvaccinated | 4,120/15,558 | Reference | Reference | Reference |
| Vaxzevria with 1 dose | 53/420 | 0.48 (0.36 to 0.63) | 0.50 (0.38 to 0.66)f | 50 (34 to 62) |
| Comirnaty with 1 dose | 12/84 | 0.54 (0.31 to 0.95) | 0.50 (0.28 to 0.88)f | 50 (12 to 72) |
| Comirnaty with 2 doses | 15/336 | 0.17 (0.10 to 0.28) | 0.15 (0.09 to 0.26)f | 85 (74 to 91) |
| Relative effect of 2 vs 1 dose of Comirnaty | 15/336 vs 12/84 | 0.31 (0.15 to 0.67) | 0.31 (0.15 to 0.67) | 69 (33 to 85) |
| Symptomatic COVID-19 in ≥ 60 year age group | ||||
| Unvaccinated | 1,186/4,022 | Reference | Reference | Reference |
| Vaxzevria with 1 dose | 14/104 | 0.46 (0.27 to 0.77) | 0.47 (0.28 to 0.81)f | 53 (19 to 72) |
| Comirnaty with 1 dose | 50/226 | 0.75 (0.57 to 1.00) | 0.80 (0.60 to 1.07)f | 20 (−7 to 40) |
| Comirnaty with 2 doses | 10/155 | 0.22 (0.12 to 0.41) | 0.24 (0.13 to 0.45)f | 76 (55 to 87) |
| Relative effect of 2 vs 1 dose of Comirnaty | 10/155 vs 50/226 | 0.29 (0.15 to 0.58) | 0.30 (0.15 to 0.60) | 70 (40 to 85) |
CI: confidence interval; COVID-19: coronavirus disease; RR: relative risk; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; VE: vaccine effectiveness.
a Vaxzevria (ChAdOx1 nCoV-19, Oxford-AstraZeneca, Cambridge, United Kingdom).
b Comirnaty (BNT162b2 mRNA, BioNTech-Pfizer, Mainz, Germany/New York, United States).
c The number of individuals who received the Moderna COVID-19 Vaccine (mRNA-1273, Moderna, Cambridge, United States) was too low to estimate vaccine effectiveness.
d RR adjusted by age groups (18–39, 40–59 and ≥ 60 years), sex, contact setting (household or other), major chronic conditions and month.
e Asymptomatic and symptomatic COVID-19 infections.
f Interaction between age group and vaccination with one dose of Vaxzevria (p = 0.809), vaccination with one dose of Comirnaty (p = 0.179) and vaccination with two doses of Comirnaty (p = 0.327).
Comparison of brands should be avoided from this study since they were not randomly distributed.