Table 2.

Risk of subsequent infection with type- and group-specific HPV by baseline serum antibody status

Baseline serum antibody statusHPV type acquired subsequentlyNo. of persons at riskNo. of incident casesPerson-monthsIncidence rate (per 1,000 person-months)IRR (95% CI)
Anti-HPV 16 antibody
    SeropositiveHPV 164135365.61.1 (0.3-4.0)
    Seronegative235153,0764.91.0
    SeropositiveHPV 16–related types*3925153.90.6 (0.1-2.6)
    Seronegative231192,9966.31.0
    SeropositiveOther HPV types301135331.11.2 (0.6-2.4)
    Seronegative176522,07325.11.0
Anti-HPV 18 antibody
    SeropositiveHPV 186018091.21.8 (0.2-20.2)
    Seronegative22322,9660.71.0
    SeropositiveHPV 18–related types5537274.10.6 (0.2-2.0)
    Seronegative211192,7766.81.0
    SeropositiveOther HPV types411546532.31.3 (0.7-2.3)
    Seronegative168491,98824.61.0
  • *HPV 16–related types include HPV 31, 33, 35, 52, 58, and 67.

  • HPV 18–related types include HPV 39, 45, 59, 68, and 70.