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Impact of vaccination on 14 high-risk HPV type infections: a mathematical modelling approach.

Vänskä S, Auranen K, Leino T, Salo H, Nieminen P, Kilpi T, Tiihonen P, Apter D, Lehtinen M - PLoS ONE (2013)

Bottom Line: The analysis disclosed the important role of persistent infections in hrHPV epidemiology, provided further evidence for a significant natural immunity, and demonstrated the dependence of transmission probability estimates on the model structure.In males, the reduction will be 42% in the hrHPV prevalence solely by the herd effect from the 80% coverage in girls.On the other hand, any herd effects in older unvaccinated cohorts were minor.

View Article: PubMed Central - PubMed

Affiliation: Department of Vaccination and Immune Protection, National Institute for Health and Welfare (THL), Helsinki, Finland. simopekka.vanska@thl.fi

ABSTRACT
The development of high-risk human papillomavirus (hrHPV) infection to cervical cancer is a complicated process. We considered solely hrHPV infections, thus avoiding the confounding effects of disease progression, screening, and treatments. To analyse hrHPV epidemiology and to estimate the overall impact of vaccination against infections with hrHPVs, we developed a dynamic compartmental transmission model for single and multiple infections with 14 hrHPV types. The infection-related parameters were estimated using population-based sexual behaviour and hrHPV prevalence data from Finland. The analysis disclosed the important role of persistent infections in hrHPV epidemiology, provided further evidence for a significant natural immunity, and demonstrated the dependence of transmission probability estimates on the model structure. The model predicted that vaccinating girls at 80% coverage will result in a 55% reduction in the overall hrHPV prevalence and a higher 65% reduction in the prevalence of persistent hrHPV infections in females. In males, the reduction will be 42% in the hrHPV prevalence solely by the herd effect from the 80% coverage in girls. If such high coverage among girls is not reached, it is still possible to reduce the female hrHPV prevalence indirectly by the herd effect if also boys are included in the vaccination program. On the other hand, any herd effects in older unvaccinated cohorts were minor. Limiting the epidemiological model to infection yielded improved understanding of the hrHPV epidemiology and of mechanisms with which vaccination impacts on hrHPV infections.

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Related in: MedlinePlus

Transmission Model Structure for a Single HPV Type.The vertical flow corresponds to changes in the epidemiologic states susceptible (S), infectious (I), recovered (R), and vaccine-protected (V). The flow from left to right corresponds to an increasing lifetime partner number (n). The arrows describe possible transitions between different states: 1. Acquisition of a new partner without acquiring infection; 2. Acquisition of a new partner with acquiring infection (primary force of infection); 3. Acquisition of infection from the current partner (secondary force of infection, for n >0 only); 4. Clearance of infection; 5. Waning natural immunity; 6–7 and 10. Acquisition of a new partner for infected, recovered, and vaccine protected; 8. Take of vaccine protection; 9. Waning vaccine induced protection. The formulae for all transition rates are presented in File S1.
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pone-0072088-g003: Transmission Model Structure for a Single HPV Type.The vertical flow corresponds to changes in the epidemiologic states susceptible (S), infectious (I), recovered (R), and vaccine-protected (V). The flow from left to right corresponds to an increasing lifetime partner number (n). The arrows describe possible transitions between different states: 1. Acquisition of a new partner without acquiring infection; 2. Acquisition of a new partner with acquiring infection (primary force of infection); 3. Acquisition of infection from the current partner (secondary force of infection, for n >0 only); 4. Clearance of infection; 5. Waning natural immunity; 6–7 and 10. Acquisition of a new partner for infected, recovered, and vaccine protected; 8. Take of vaccine protection; 9. Waning vaccine induced protection. The formulae for all transition rates are presented in File S1.

Mentions: Figure 3 presents the structure of the transmission model for a single hrHPV type (for formulae, see Table S4 in File S1). The force of infection was divided into primary and secondary components, according to whether infection is acquired from a new partner or from the current one who has sex with someone else (secondary contact). The importance of the secondary force of infection was controlled with a weight parameter γ, which describes the intensity of individuals making secondary contacts.


Impact of vaccination on 14 high-risk HPV type infections: a mathematical modelling approach.

Vänskä S, Auranen K, Leino T, Salo H, Nieminen P, Kilpi T, Tiihonen P, Apter D, Lehtinen M - PLoS ONE (2013)

Transmission Model Structure for a Single HPV Type.The vertical flow corresponds to changes in the epidemiologic states susceptible (S), infectious (I), recovered (R), and vaccine-protected (V). The flow from left to right corresponds to an increasing lifetime partner number (n). The arrows describe possible transitions between different states: 1. Acquisition of a new partner without acquiring infection; 2. Acquisition of a new partner with acquiring infection (primary force of infection); 3. Acquisition of infection from the current partner (secondary force of infection, for n >0 only); 4. Clearance of infection; 5. Waning natural immunity; 6–7 and 10. Acquisition of a new partner for infected, recovered, and vaccine protected; 8. Take of vaccine protection; 9. Waning vaccine induced protection. The formulae for all transition rates are presented in File S1.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3756967&req=5

pone-0072088-g003: Transmission Model Structure for a Single HPV Type.The vertical flow corresponds to changes in the epidemiologic states susceptible (S), infectious (I), recovered (R), and vaccine-protected (V). The flow from left to right corresponds to an increasing lifetime partner number (n). The arrows describe possible transitions between different states: 1. Acquisition of a new partner without acquiring infection; 2. Acquisition of a new partner with acquiring infection (primary force of infection); 3. Acquisition of infection from the current partner (secondary force of infection, for n >0 only); 4. Clearance of infection; 5. Waning natural immunity; 6–7 and 10. Acquisition of a new partner for infected, recovered, and vaccine protected; 8. Take of vaccine protection; 9. Waning vaccine induced protection. The formulae for all transition rates are presented in File S1.
Mentions: Figure 3 presents the structure of the transmission model for a single hrHPV type (for formulae, see Table S4 in File S1). The force of infection was divided into primary and secondary components, according to whether infection is acquired from a new partner or from the current one who has sex with someone else (secondary contact). The importance of the secondary force of infection was controlled with a weight parameter γ, which describes the intensity of individuals making secondary contacts.

Bottom Line: The analysis disclosed the important role of persistent infections in hrHPV epidemiology, provided further evidence for a significant natural immunity, and demonstrated the dependence of transmission probability estimates on the model structure.In males, the reduction will be 42% in the hrHPV prevalence solely by the herd effect from the 80% coverage in girls.On the other hand, any herd effects in older unvaccinated cohorts were minor.

View Article: PubMed Central - PubMed

Affiliation: Department of Vaccination and Immune Protection, National Institute for Health and Welfare (THL), Helsinki, Finland. simopekka.vanska@thl.fi

ABSTRACT
The development of high-risk human papillomavirus (hrHPV) infection to cervical cancer is a complicated process. We considered solely hrHPV infections, thus avoiding the confounding effects of disease progression, screening, and treatments. To analyse hrHPV epidemiology and to estimate the overall impact of vaccination against infections with hrHPVs, we developed a dynamic compartmental transmission model for single and multiple infections with 14 hrHPV types. The infection-related parameters were estimated using population-based sexual behaviour and hrHPV prevalence data from Finland. The analysis disclosed the important role of persistent infections in hrHPV epidemiology, provided further evidence for a significant natural immunity, and demonstrated the dependence of transmission probability estimates on the model structure. The model predicted that vaccinating girls at 80% coverage will result in a 55% reduction in the overall hrHPV prevalence and a higher 65% reduction in the prevalence of persistent hrHPV infections in females. In males, the reduction will be 42% in the hrHPV prevalence solely by the herd effect from the 80% coverage in girls. If such high coverage among girls is not reached, it is still possible to reduce the female hrHPV prevalence indirectly by the herd effect if also boys are included in the vaccination program. On the other hand, any herd effects in older unvaccinated cohorts were minor. Limiting the epidemiological model to infection yielded improved understanding of the hrHPV epidemiology and of mechanisms with which vaccination impacts on hrHPV infections.

Show MeSH
Related in: MedlinePlus