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Differences in incidence and co‐occurrence of vaccine and nonvaccine human papillomavirus types in Finnish population before human papillomavirus mass vaccination suggest competitive advantage for HPV33
Author(s) -
Merikukka Marko,
Kaasila Marjo,
Namujju Proscovia B.,
Palmroth Johanna,
Kirnbauer Reinhard,
Paavonen Jorma,
Surcel HeljäMarja,
Lehtinen Matti
Publication year - 2010
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.25675
Subject(s) - medicine , vaccination , confidence interval , population , gynecology , incidence (geometry) , demography , human papillomavirus , hpv infection , immunology , obstetrics , cervical cancer , cancer , physics , environmental health , sociology , optics
To understand likelihood of type replacement after vaccination against the high‐risk human papillomavirus (HPV) types, we evaluated competition of the seven most common genital HPV types in a population sample of unvaccinated, fertile‐aged Finnish women. First trimester sera from two consecutive pregnancies were retrieved from 3,183 Finnish women (mean age, 23.1 years) of whom 42.3% had antibodies to at least one HPV type (6/11/16/18/31/33/45) at the baseline. Antibody positivity to more than one HPV types by the second pregnancy was common among the baseline HPV seropositives. However, compared to baseline HPV‐seronegative women, significantly increased incidence rate ratios (IRRs), indicating an increased risk to seroconvert for another HPV type, were consistently noted only for HPV33 among baseline HPV16 or HPV18 antibody (ab)‐positive women: HPV 16ab only → 16&33ab IRR 2.9 [95% confidence interval (CI) 1.6–5.4] and HPV 18ab only → 18&33ab IRR 2.5 (95% CI 1.1–6.0), irrespectively of the presence of antibodies to other HPV types at baseline: HPV 16ab → 16&33ab IRR 3.2 (95% CI 2.0–5.2) and HPV 18ab → 18&33ab IRR 3.6 (95% CI 2.1–5.9). Our findings suggest a possible competitive advantage for HPV33 over other genital HPV types in the unvaccinated population. HPV33 should be monitored for type replacement after HPV mass vaccination.