Table 2.
Humoral responses of individuals with ChAdOx1 nCoV-19 vaccination according to pre-existing adenovirus immunity.
| Immunogenicity | Total (n = 68) | Adenovirus Immunity | p Value | |
|---|---|---|---|---|
| Negative (n = 19, 27.9%) |
Positive (n = 49, 72.1%) |
|||
| PRNT50 a at T0 | 5.07 (3.04–9.55) | 5.35 (3.84–14.39) | 3.77 (1.43–9.35) | 0.231 |
| Spike (S)-specific IgG titers at T0 | 0.4 (0.4–0.4) | 0.4 (0.4–0.4) | 0.4 (0.4–0.4) | 0.479 |
| PRNT50 at T1 | 146.5 (57.3–271.5) | 245.2 (142.6–377.1) | 94.1 (44.4–157.5) | 0.021 b |
| S-specific IgG titers at T1 | 5.0 (0.4–31.6) | 29.6 (6.6–75.3) | 14.0 (1.6–84.5) | 0.109 |
| PRNT50 at T2 | 37.6 (19.3–100.1) | 50.0 (22.7–105.4) | 33.6 (18.9–98.4) | 0.774 |
| S-specific IgG titers at T2 | 31.9 (6.1–74.1) | 56.4 (36.6–125.0) | 51.0 (17.9–122.3) | 0.034 c |
| PRNT50 at T3 | 432.2 (163.5–904.8) | 647.5 (283.2–1014.3) | 352.4 (149.2–867.9) | 0.292 |
| S-specific IgG titers at T3 | 415.5 (165.3–831.0) | 629.5 (451.5–926.5) | 555.0 (287.3–926.0) | 0.049 c |
| PRNT50 at T4 | 117.8 (89.8–262.3) | 245.1 (96.5–432.2) | 108.8 (85.8–166.5) | 0.065 |
| S-specific IgG titers at T4 | 245.0 (141.3–339.0) | 274.5 (160.5–655.3) | 176.0 (94.3–255.3) | 0.033 c |
| Seroconversion rate | ||||
| After the first dose | 51 (75.0%) | 16 (84.2%) | 35 (71.4%) | 0.359 |
| After the second dose | 68 (100.0%) | 19 (100.0%) | 49 (100.0%) | |
a PRNT50: Plaque reduction neutralization test, highest serum dilution that resulted in >50% reduction in viral plaques. b The PRNT50 at T1 was statistically higher in individuals without pre-existing Ad immunity. c The geometric mean titer of S-specific IgG antibodies at T2, T3, and T4 was statistically higher in individuals without pre-existing Ad immunity. T0, before the first ChAdOx1 nCoV-19 dose; T1, 2–3 weeks after the first ChAdOx1 nCoV-19 dose; T2, before the second ChAdOx1 nCoV-19 dose; T3, 2–3 weeks after the second ChAdOx1 nCoV-19 dose; T4, 3 months after the second ChAdOx1 nCoV-19 dose.