Table 2.
Antibody avidity over time among one-dose and three-dose participants, stratified by HPV16 serostatus at first HPV vaccination.
| Study visit | One dose (N = 774) | Three dose (N = 1158) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| HPV16 seronegative | HPV16 seropositive | Seropositive/Seronegative | HPV16 seronegative | HPV16 seropositive | Seropositive/Seronegative | |||||||||
| n | GMA (95% CI) | % change† | n | GMA (95% CI) | % change† | Ratio (95% CI) | n | GMA (95% CI) | % change† | n | GMA (95% CI) | % change† | Ratio (95% CI) | |
| First HPV vaccination | 0 | N/A | N/A | 27 | 0.78 (0.53–1.15) | N/A | N/A | 0 | N/A | N/A | 43 | 0.97 (0.79–1.20) | N/A | N/A |
| Year 1 | 42 | 2.39 (2.13–2.68) | N/A | 10 | 1.39 (0.88–2.18) | 77.0 | 0.58 (0.36–0.93) | 117 | 2.87 (2.80–2.94) | N/A | 44 | 2.44 (2.16–2.76) | 150.4 | 0.85 (0.75–0.96) |
| Year 2 | 47 | 2.62 (2.44–2.82) | 9.8 | 9 | 1.81 (1.25–2.62) | 30.5 | 0.69 (0.47–1.00) | 109 | 2.99 (2.89–3.09) | 4.0 | 33 | 2.31 (1.95–2.74) | −5.2 | 0.77 (0.65–0.92) |
| Year 3 | 44 | 2.81 (2.67–2.96) | 7.2 | 7 | 1.50 (0.94–2.38) | −17.2 | 0.53 (0.33–0.85) | 93 | 2.98 (2.90–3.07) | −0.2 | 26 | 2.65 (2.36–2.98) | 14.5 | 0.89 (0.79–1.00) |
| Year 4 | 81 | 2.76 (2.62–2.90) | −1.9 | 42 | 1.74 (1.47–2.06) | 16.3 | 0.63 (0.53–0.75) | 152 | 3.02 (2.97–3.07) | 1.2 | 39 | 2.47 (2.18–2.80) | −6.9 | 0.82 (0.72–0.93) |
| Year 7 | 119 | 2.76 (2.66–2.86) | 0.1 | 43 | 2.00 (1.75–2.30) | 15.2 | 0.73 (0.63–0.84) | 168 | 3.07 (3.01–3.13) | 1.8 | 57 | 2.52 (2.26–2.82) | 2.2 | 0.82 (0.73–0.92) |
| Year 9 | 82 | 2.73 (2.55–2.92) | −1.1 | 43 | 1.78 (1.48–2.15) | −10.9 | 0.65 (0.54–0.80) | 106 | 3.05 (2.98–3.12) | −0.8 | 30 | 2.43 (2.07–2.84) | −3.7 | 0.80 (0.68–0.93) |
| Year 11 | 125 | 2.70 (2.60–2.80) | −1.2 | 53 | 1.82 (1.55–2.13) | 1.9 | 0.67 (0.57–0.79) | 108 | 3.02 (2.94–3.11) | −0.8 | 33 | 2.55 (2.28–2.84) | 5.0 | 0.84 (0.75–0.94) |
| Overall* | 540 | 2.70 (2.61–2.80) | 234 | 1.80 (1.55–2.08) | 0.66 (0.57–0.77) | 853 | 3.01 (2.96–3.05) | 305 | 2.48 (2.27–2.71) | 0.82 (0.75–0.90) | ||||
| p-for-trend** | 0.28 | 0.79 | 0.85 | 0.82 | ||||||||||
N total number of samples, n number of samples tested per study visit, GMA Geometric Mean of the Avidity Index, CI confidence intervals, N/A not applicable.
†% change was calculated based on two consecutive visits.
*Overall GMAs calculated over years 1–11. P value comparing overall GMA ratios was 0.017, presented in bold.
** p-for-trend within dose group, over time in years 4–11.