Table 2.
Estimated neutralizing antibody titers against ancestral SARS-CoV-2 (D614G) and the Beta variant after the mRNA-1273 primary series and after the 50-µg and 100-µg booster dose of mRNA-1273.211
| Ancestral SARS-CoV-2 (D614G) | Beta (B.1.351) | Ancestral SARS-CoV-2 (D614G) | ||
|---|---|---|---|---|
| 50-µg, mRNA-1273.211 booster dose | Historical control, 100-µg mRNA-1273 primary series | 50-µg, mRNA-1273.211 booster dose | Historical control, 100-µg mRNA-1273 primary series | |
| n = 299 | n = 584 | n = 299 | n = 584 | |
| Pre-vaccination baseline, n† | 299 | 584 | 297 | 584 |
| GMT (95% CI)§ | 9.4 (9.1–9.7) | 9.7 (9.3–10.1) | 9.8 (NE–NE) | 9.7 (9.3–10.1) |
| 28 days after booster or 2nd dose, n | 299 | 584 | 299 | 584 |
| Estimated GMT (95% CI)¶ | 1,996.2 (1,777.9–2,241.4) | 1,053.4 (967.2–1,147.2) | 953.9 (844.1–1,078.0) | 1,058.0 (966.9–1,157.7) |
| GMR (mRNA-1273.211-50-µg versus 100-µg mRNA-1273) (95% CI) | 1.9 (1.7–2.2) | 0.9 (0.8–1.0) | ||
| SRRs n/N1 (%) (versus pre-vaccination)ǁ | 295/299 (98.7) | 573/584 (98.1) | 291/297 (98.0) | 573/584 (98.1) |
| (95% CI)‡ | 96.6–99.6 | 96.7–99.1 | 95.7–99.3 | 96.7–99.1 |
| Difference % (95% CI)†† | 0.5 (−1.6 to 2.2) | −0.1 (−2.6 to 1.7) | ||
| 100-µg, mRNA-1273.211 booster dose | Historical control, 100-µg mRNA-1273 primary series | 100-µg, mRNA-1273.211 booster dose | Historical control, 100-µg mRNA-1273 primary series | |
|---|---|---|---|---|
| n = 578 | n = 584 | n = 584 | n = 584 | |
| Pre-vaccination baseline n† | 578 | 584 | 571 | 584 |
| GMT (95% CI)§ | 9.4 (9.2–9.5) | 9.7 (9.3–10.1) | 9.8 (9.7–9.9) | 9.7 (9.3–10.1) |
| 28 days after booster or 2nd dose, n | 578 | 584 | 578 | 584 |
| Estimated GMT (95% CI)¶ | 4,324.7 (3,974.6–4,705.6) | 1,087.3 (999.7–1,182.6) | 1,574.6 (1,439.4–1,722.5) | 1,085.7 (992.9–1,187.2) |
| GMR (mRNA-1273.211-100-µg versus 100-µg mRNA-1273) (95% CI) | 4.0 (3.6–4.4) | 1.5 (1.3–1.6) | ||
| SRRs n/N1 (%) (versus pre-vaccination)ǁ | 577/578 (99.8) | 573/584 (98.1) | 566/571 (99.1) | 573/584 (98.1) |
| (95% CI)‡ | (99.0–100.0) | (96.7–99.1) | (98.0–99.7) | (96.7–99.1) |
| Difference % (95% CI)†† | 1.7 (0.7–3.2) | 1.0 (−0.4 to 2.6) | ||
NE, not estimated; ULOQ, upper limit of quantification.
Antibody values assessed by pseudovirus neutralizing antibody assay reported as below the LLOQ are replaced by 0.5× LLOQ, and values greater than ULOQ are replaced by the ULOQ if actual values are not available.
*Beta-specific antibody data are shown for the mRNA-1273.211 booster and for the ancestral SARS-Cov-2 with D614G for the primary series historical control group.
†Pre-vaccination baseline is before the first dose of mRNA-1273 in the primary series; n indicates the number of participants with non-missing data at the timepoint (baseline or post-baseline).
§95% CI is calculated based on the t-distribution of the log-transformed values for geometric mean value and then back-transformed to the original scale for presentation.
¶The log-transformed antibody levels were analyzed using an ANCOVA model with the treatment variable as fixed effect, adjusting for age group (<65 years and ≥65 years). The treatment variable corresponds to the primary series historical control group and each individual study group (mRNA-1273.211) dose levels. The resulting least squares means, differences of the least squares means and 95% CIs are back-transformed to the original scale for presentation.
ǁSeroresponse at a participant level is defined as a change from below the LLOQ to equal to or above 4× LLOQ or at least a four-fold rise if baseline (titer before receiving the mRNA-1273 primary series) is equal to or above the LLOQ. Percentages are based on the number of participants with non-missing data at baseline and the corresponding timepoint (N1). For study participants with negative SARS-CoV-2 status before the primary series, antibody titers are imputed as <LLOQ at pre-dose 1 of the primary series. For participants without SARS-CoV-2 status information at pre-dose 1 of primary series, their pre-booster SARS-CoV-2 status was used to impute their SARS-CoV-2 status at pre-dose 1 of the primary series.
‡95% CI was calculated using the Clopper–Pearson method.
††95% CI was calculated using the Miettinen–Nurminen (score) confidence limits.