Table 2.
Efficacy against SARS-CoV-2 more than 14 days after a second dose of ChAdOx1 nCoV-19 vaccine in the primary efficacy population
| Total number of cases |
ChAdOx1 nCoV-19 |
Control |
Vaccine efficacy (CI*) | |||||
|---|---|---|---|---|---|---|---|---|
| n/N (%) | Incidence rate per 1000 person-years (person-days of follow-up) | n/N (%) | Incidence rate per 1000 person-years (person-days of follow-up) | |||||
| All LD/SD and SD/SD recipients | 131 | 30/5807 (0·5%) | 44·1 (248 299) | 101/5829 (1·7%) | 149·2 (247 228) | 70·4% (54·8 to 80·6)† | ||
| COV002 (UK) | 86 | 18/3744 (0·5%) | 38·6 (170 369) | 68/3804 (1·8%) | 145·7 (170 448) | 73·5% (55·5 to 84·2) | ||
| LD/SD recipients | 33 | 3/1367 (0·2%) | 14·9 (73 313) | 30/1374 (2·2%) | 150·2 (72 949) | 90·0% (67·4 to 97·0)§§ | ||
| SD/SD recipients | 53 | 15/2377 (0·6%) | 56·4 (97 056) | 38/2430 (1·6%) | 142·4 (97 499) | 60·3% (28·0 to 78·2) | ||
| COV003 (Brazil; all SD/SD) | 45 | 12/2063 (0·6%) | 56·2 (77 930) | 33/2025 (1·6%) | 157·0 (76 780) | 64·2% (30·7 to 81·5)‡ | ||
| All SD/SD recipients | 98 | 27/4440 (0·6%) | 56·4 (174 986) | 71/4455 (1·6%) | 148·8 (174 279) | 62·1% (41·0 to 75·7) | ||
| Other non-primary symptomatic COVID-19 disease¶ | 18 | 7/5807 (0·1%) | 10·3 (248 299) | 11/5829 (0·2%) | 16·3 (247 228) | 36·4% (−63·8 to 75·3)‡ | ||
| Any symptomatic COVID-19 disease | 149 | 37/5807 (0·6%) | 54·4 (248 299) | 112/5829 (1·9%) | 165·5 (247 228) | 67·1% (52·3 to 77·3) | ||
| Asymptomatic or symptoms unknown (COV002) | 69 | 29/3288 (0·9%) | 69·8 (151 673) | 40/3350 (1·2%) | 96·0 (152 138) | 27·3% (−17·2 to 54·9) | ||
| LD/SD recipients | 24 | 7/1120 (0·6%) | 41·4 (61 782) | 17/1127 (1·5%) | 100·6 (61 730) | 58·9% (1·0 to 82·9)‡ | ||
| SD/SD recipients | 45 | 22/2168 (1·0%) | 89·4 (89 891) | 23/2223 (1·0%) | 92·9 (90 408) | 3·8% (−72·4 to 46·3) | ||
| Any NAAT-positive swab | 221 | 68/5807 (1·2%) | 100·0 (248 299) | 153/5829 (2·6%) | 226·0 (247 228) | 55·7% (41·1 to 66·7) | ||
Vaccine efficacy was calculated from the robust Poisson model. The primary efficacy population (LD/SD and SD/SD) includes randomly assigned participants who were seronegative at baseline and received LD/SD or SD/SD or were in a corresponding control group, and remained on study more than 14 days after their second dose without having had a previous virologically confirmed SARS-CoV-2 infection. In addition, for groups in COV002, only efficacy groups (ie, groups 4, 6, 9, and 10) are included. SARS-CoV-2=severe acute respiratory syndrome coronavirus 2. LD/SD=low-dose prime plus standard-dose boost. SD/SD=two standard-dose vaccines given. NAAT=nucleic acid amplification test.
CIs are 95% unless indicated otherwise.
95·8% CI used for primary analysis.
Vaccine efficacy calculated from a reduced robust Poisson model that was not adjusted for age. All other models included an adjustment for age.
p value for interaction term comparing LD/SD with SD/SD is p=0·010.
Other non-primary symptomatic COVID-19 disease includes cases who have symptoms other than the five main symptoms that are required for inclusion in the primary analysis (eg, a participant who has diarrhoea and malaise but no fever, cough, shortness of breath, anosmia, or ageusia).