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Incremental benefits of male HPV vaccination: accounting for inequality in population uptake.

Smith MA, Canfell K - PLoS ONE (2014)

Bottom Line: Cultural and geographic factors associated with HPV vaccine uptake might also influence sexual partner choice; this might impact post-vaccination outcomes.The rate ratio for post-vaccination incident HPV16 in the lowest compared to the highest coverage subgroup (RR(L)) was calculated to quantify between-group differences in outcomes.The population-level incremental impact of adding males was lower if vaccine uptake was "correlated", however the difference in population-level impact was extremely small (<1%) in the Australia and USA scenarios, even under the conservative and extreme assumption that subgroups according to coverage did not mix at all sexually.

View Article: PubMed Central - PubMed

Affiliation: School of Public Health, The University of Sydney, Sydney, Australia; Prince of Wales Clinical School, UNSW Australia, Sydney, Australia.

ABSTRACT

Background: Vaccines against HPV16/18 are approved for use in females and males but most countries currently have female-only programs. Cultural and geographic factors associated with HPV vaccine uptake might also influence sexual partner choice; this might impact post-vaccination outcomes. Our aims were to examine the population-level impact of adding males to HPV vaccination programs if factors influencing vaccine uptake also influence partner choice, and additionally to quantify how this changes the post-vaccination distribution of disease between subgroups, using incident infections as the outcome measure.

Methods: A dynamic model simulated vaccination of pre-adolescents in two scenarios: 1) vaccine uptake was correlated with factors which also affect sexual partner choice ("correlated"); 2) vaccine uptake was unrelated to these factors ("unrelated"). Coverage and degree of heterogeneity in uptake were informed by observed data from Australia and the USA. Population impact was examined via the effect on incident HPV16 infections. The rate ratio for post-vaccination incident HPV16 in the lowest compared to the highest coverage subgroup (RR(L)) was calculated to quantify between-group differences in outcomes.

Results: The population-level incremental impact of adding males was lower if vaccine uptake was "correlated", however the difference in population-level impact was extremely small (<1%) in the Australia and USA scenarios, even under the conservative and extreme assumption that subgroups according to coverage did not mix at all sexually. At the subgroup level, "correlated" female-only vaccination resulted in RR(L)= 1.9 (Australia) and 1.5 (USA) in females, and RR(L)= 1.5 and 1.3 in males. "Correlated" both-sex vaccination increased RR(L) to 4.2 and 2.1 in females and 3.9 and 2.0 in males in the Australia and USA scenarios respectively.

Conclusions: The population-level incremental impact of male vaccination is unlikely to be substantially impacted by feasible levels of heterogeneity in uptake. However, these findings emphasize the continuing importance of prioritizing high coverage across all groups in HPV vaccination programs in terms of achieving equality of outcomes.

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Related in: MedlinePlus

Subgroup size and vaccine uptake in modelled coverage scenarios.Values next to bar represent coverage in that subgroup; bar height represents subgroup size.
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pone-0101048-g001: Subgroup size and vaccine uptake in modelled coverage scenarios.Values next to bar represent coverage in that subgroup; bar height represents subgroup size.

Mentions: However, the scenarios chosen were informed by data from actual HPV vaccination experiences. Three population coverage scenarios were considered: “Australia” (72% overall); “USA” (32% overall); and a hypothetical exploratory scenario with intermediate coverage (50% overall) where the “correlated” variant explored “extreme inequality”. The “Australia” coverage scenario was based on observed vaccine uptake in Australia for girls aged 15 years in 2009 (who were offered vaccination in 2007 and 2008). Three subgroups were formed, with their size and vaccine coverage based on three-dose uptake within the different states, grouped based on broad coverage levels [36], [37]. Uptake in the subgroups ranged from 64.5% to 76.3%. The “USA” population coverage scenario was based on observed vaccine uptake for females in the USA who were aged 13 to 17 years in 2010. Four subgroups were formed, with their size and vaccine coverage likewise based on three-dose uptake within the different states grouped based on broad coverage levels [38], [39]. Uptake in the subgroups ranged from 23.0% to 43.6%. In each coverage scenario, the equivalent overall population coverage used in the “unrelated” variant of the scenario was the weighted average of three-dose coverage across all subgroups. Detailed information on coverage assumptions in each case is presented in Figure 1 and Table S1 in File S1.


Incremental benefits of male HPV vaccination: accounting for inequality in population uptake.

Smith MA, Canfell K - PLoS ONE (2014)

Subgroup size and vaccine uptake in modelled coverage scenarios.Values next to bar represent coverage in that subgroup; bar height represents subgroup size.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4121069&req=5

pone-0101048-g001: Subgroup size and vaccine uptake in modelled coverage scenarios.Values next to bar represent coverage in that subgroup; bar height represents subgroup size.
Mentions: However, the scenarios chosen were informed by data from actual HPV vaccination experiences. Three population coverage scenarios were considered: “Australia” (72% overall); “USA” (32% overall); and a hypothetical exploratory scenario with intermediate coverage (50% overall) where the “correlated” variant explored “extreme inequality”. The “Australia” coverage scenario was based on observed vaccine uptake in Australia for girls aged 15 years in 2009 (who were offered vaccination in 2007 and 2008). Three subgroups were formed, with their size and vaccine coverage based on three-dose uptake within the different states, grouped based on broad coverage levels [36], [37]. Uptake in the subgroups ranged from 64.5% to 76.3%. The “USA” population coverage scenario was based on observed vaccine uptake for females in the USA who were aged 13 to 17 years in 2010. Four subgroups were formed, with their size and vaccine coverage likewise based on three-dose uptake within the different states grouped based on broad coverage levels [38], [39]. Uptake in the subgroups ranged from 23.0% to 43.6%. In each coverage scenario, the equivalent overall population coverage used in the “unrelated” variant of the scenario was the weighted average of three-dose coverage across all subgroups. Detailed information on coverage assumptions in each case is presented in Figure 1 and Table S1 in File S1.

Bottom Line: Cultural and geographic factors associated with HPV vaccine uptake might also influence sexual partner choice; this might impact post-vaccination outcomes.The rate ratio for post-vaccination incident HPV16 in the lowest compared to the highest coverage subgroup (RR(L)) was calculated to quantify between-group differences in outcomes.The population-level incremental impact of adding males was lower if vaccine uptake was "correlated", however the difference in population-level impact was extremely small (<1%) in the Australia and USA scenarios, even under the conservative and extreme assumption that subgroups according to coverage did not mix at all sexually.

View Article: PubMed Central - PubMed

Affiliation: School of Public Health, The University of Sydney, Sydney, Australia; Prince of Wales Clinical School, UNSW Australia, Sydney, Australia.

ABSTRACT

Background: Vaccines against HPV16/18 are approved for use in females and males but most countries currently have female-only programs. Cultural and geographic factors associated with HPV vaccine uptake might also influence sexual partner choice; this might impact post-vaccination outcomes. Our aims were to examine the population-level impact of adding males to HPV vaccination programs if factors influencing vaccine uptake also influence partner choice, and additionally to quantify how this changes the post-vaccination distribution of disease between subgroups, using incident infections as the outcome measure.

Methods: A dynamic model simulated vaccination of pre-adolescents in two scenarios: 1) vaccine uptake was correlated with factors which also affect sexual partner choice ("correlated"); 2) vaccine uptake was unrelated to these factors ("unrelated"). Coverage and degree of heterogeneity in uptake were informed by observed data from Australia and the USA. Population impact was examined via the effect on incident HPV16 infections. The rate ratio for post-vaccination incident HPV16 in the lowest compared to the highest coverage subgroup (RR(L)) was calculated to quantify between-group differences in outcomes.

Results: The population-level incremental impact of adding males was lower if vaccine uptake was "correlated", however the difference in population-level impact was extremely small (<1%) in the Australia and USA scenarios, even under the conservative and extreme assumption that subgroups according to coverage did not mix at all sexually. At the subgroup level, "correlated" female-only vaccination resulted in RR(L)= 1.9 (Australia) and 1.5 (USA) in females, and RR(L)= 1.5 and 1.3 in males. "Correlated" both-sex vaccination increased RR(L) to 4.2 and 2.1 in females and 3.9 and 2.0 in males in the Australia and USA scenarios respectively.

Conclusions: The population-level incremental impact of male vaccination is unlikely to be substantially impacted by feasible levels of heterogeneity in uptake. However, these findings emphasize the continuing importance of prioritizing high coverage across all groups in HPV vaccination programs in terms of achieving equality of outcomes.

Show MeSH
Related in: MedlinePlus