Table 5.
Incidence rates of symptomatic infection in mRNA-1273 and BNT162b2 cohorts
| Study design | Time period | mRNA-1273 incidence rate [cases/1,000 at-risk person days] (number of individuals) | BNT162b2 incidence rate [cases/1,000 at-risk person days] (number of individuals) | Incidence rate ratio (95% CI) |
|---|---|---|---|---|
| Unmatched cohorts (per protocol) | days 1–10 after first dose | 126/550,143.0 [0.23] (n = 55,201) | 236/1,085,498.0 [0.22] (n = 108,922) | 1.1 (0.84, 1.3) |
| study duration | 498/7,388,249.0 [0.067] (n = 45,534) | 1,389/15,342,928.0 [0.091] (n = 92,547) | 0.74 (0.67, 0.83) | |
| early epoch | 22/2,508,776.0 [0.0088] (n = 41,279) | 76/5,589,957.0 [0.014] (n = 82,615) | 0.64 (0.38, 1) | |
| late epoch | 464/3,550,304.0 [0.13] (n = 45,279) | 1,279/7,115,229.0 [0.18] (n = 92,074) | 0.73 (0.65, 0.81) | |
| Matched cohorts (per protocol) | days 1–10 after first dose | 51/207,988.0 [0.25] (n = 20,862) | 35/208,403.0 [0.17] (n = 20,882) | 1.5 (0.93, 2.3) |
| study duration | 139/2,470,204 [0.056] (n = 15,392) | 215/2,461,985 [0.087] (n = 15,392) | 0.64 (0.52, 0.8) | |
| early epoch | 9/799,534.0 [0.011] (n = 14,351) | 12/793,719.0 [0.015] (n = 14,389) | 0.74 (0.28, 1.9) | |
| late epoch | 125/1,211,346.0 [0.1] (n = 15,329) | 197/1,209,463.0 [0.16] (n = 15,310) | 0.63 (0.5, 0.8) | |
| Matched cohorts (intention to treat) | days 1–10 after first dose | 51/208,643 [0.24] (n = 20,890) | 35/208,574.0 [0.17] (n = 20,889) | 1.5 (0.93, 2.3) |
| study duration | 191/3,265,571.0 [0.058] (n = 20,469) | 288/3,260,428.0 [0.088] (n = 20,493) | 0.66 (0.55, 0.8) | |
| early epoch | 10/1,027,749.0 [0.0097] (n = 18,565) | 16/1,025,958.0 [0.016] (n = 18,596) | 0.62 (0.25, 1.5) | |
| late epoch | 176/1,637,131.0 [0.11] (n = 20,379) | 265/1,633,836.0 [0.16] (n = 20,388) | 0.66 (0.54, 0.81) |
The “study duration,” “early epoch,” and “late epoch” rows give the incidence rates of breakthrough symptomatic infections (i.e., positive symptomatic tests occurring after the date of full vaccination). The “days 1–10 after first dose” rows serve as a proxy for the baseline rate of symptomatic infection in these cohorts prior to the onset of vaccine effectiveness. Data are shown for three study designs that were tested: an unmatched per-protocol cohort study, a matched per-protocol cohort study, and a matched intention-to-treat cohort study. In the per-protocol designs, the study duration, early epoch, and late epoch rows consider individuals who received two vaccine doses according to the recommended schedule and were at risk for infection 14 days after their second dose. In the intention-to-treat design, these rows consider any individuals who received at least one dose and were at risk for infection 42 or 35 days after the first dose of mRNA-1273 or BNT162b2, respectively.