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Table 3 Persistence rates (PR) and persistence rate ratios (PRR) for HPV16/18 and HPV31/33/45 (vaccine and cross-protective types) over time, in years since vaccination

From: Measuring vaccine effectiveness against persistent HPV infections: a comparison of different statistical approaches

Yrs. Since vaccination Vaccination status N Vaccine types (HPV16/18) Cross-protective types (HPV31/33/45)
# infections PR per 100 PY (95%CI) PRR (95%CI) # infections PR per 100 PY (95%CI) PRR (95%CI)
2 Unvaccinated 551 2 0.18 (0.05–0.73)   2 0.18 (0.05–0.73) Ref
  Vaccinated 626 0 0.00 (0.00–0.59)   1 0.08 (0.01–0.57) 0.44 (0.04–4.85)
3 Unvaccinated 513 2 0.19 (0.05–0.78)   2 0.19 (0.05–0.78) Ref
  Vaccinated 567 0 0.00 (0.00–0.65)   2 0.18 (0.04–0.71) 0.90 (0.13–6.42)
4 Unvaccinated 472 7 0.74 (0.35–1.56)   4 0.42 (0.16–1.13) Ref
  Vaccinated 515 0 0.00 (0.00–0.72)   3 0.29 (0.09–0.90) 0.69 (0.15–3.074)
5 Unvaccinated 455 10 1.10 (0.59–2.04)   3 0.33 (0.11–1.02) Ref
  Vaccinated 472 0 0.00 (0.00–0.78)   1 0.11 (0.01–0.75) 0.32 (0.03–3.09)
6 Unvaccinated 447 18 2.01 (1.27–3.20) Ref 12 1.34 (0.76–2.36) Ref
  Vaccinated 438 1 0.11 (0.02–0.81) 0.06 (0.01–0.42) 2 0.23 (0.06–0.91) 0.17 (0.04–0.76)
7 Unvaccinated 433 11 1.27 (0.70–2.99) Ref 5 0.58 (0.24–1.39)  
  Vaccinated 448 2 0.22 (0.06–0.89) 0.18 (0.04–0.79) 0 0.00 (0.00–0.82)  
8 Unvaccinated 414 6 0.72 (0.33–1.61)   9 1.09 (0.57–2.09) Ref
  Vaccinated 429 0 0.00 (0.00–0.86)   5 0.58 (0.24–1.40) 0.54 (0.18–0.60)
  1. PR = persistence rate (with 95%CI), PRR = persistence rate ratio (with 95%CI), py = person years, Yrs = years
  2. * Trend in persistence rate over time for HPV16/18 among unvaccinated, p < 0.01, among vaccinated p = 0.14
  3. ** Trend in persistence rate over time for HPV31/33/45 among unvaccinated, p < 0.01, among vaccinated p = 0.17