Table 2.
Neutralizing antibody levels to ancestral strain, Delta variant, BA.1, and BA.2 measured at four time points during the study period
| Ancestral strain | Delta variant | BA.1 | BA.2 | ||
|---|---|---|---|---|---|
| G1: HCWs without prior BI | 2 weeks after D2 | 86.2 (74.6–93.8) | 86.3 (74.4–89.8) | −4.7 (–12 to 9.5) | 6.1 (2.9–14.4) |
| Before D3 | 26.9 (19.1–36.2) | 7.5 (–5.3–17.5) | −3.2 (–5.5 to –1) | 0 (0–3.3) | |
| 2 weeks after D3 | 97.3 (96.9–97.5) | 98.2 (98.0–98.3) | 84.1 (74.1–90.6) | 92.7 (89.2–95.6) | |
| 15 weeks after D3 | 97.5 (97.4–97.6) | 97.9 (97.4–98.1) | 54.3 (19.1–92.1) | 83.7 (68.3–97.6) | |
| G2: HCWs with prior BI | 2 weeks after BI | 96.9 (81.6–97.0) | 97.6 (77.2–98.2) | 70.0 (10.9–80.8) | 85.7 (–5.2 to 92.4) |
| Before D3 | 96.0 (87.8–96.6) | 97.5 (71.9–98) | 18.8 (6–46.7) | 74.1 (34.5–82.9) | |
| 2 weeks after D3 | 96.1 (95.8–97.5) | 98.1 (98.0–98.4) | 92.3 (82.8–95.7) | 95.7 (90.8–97.7) | |
| 15 weeks after D3 | 96.8 (96.7–97.0) | 98 (98.0–98.2) | 87.8 (70.5–93.2) | 94.9 (89.0–98.2) |
BI = breakthrough infection; D2 = dose 2; D3 = dose 3; HCW = healthcare worker. Reported values are median inhibition in % (interquartile range).