<![CDATA[Elimination of HPV from different countries]]>

Dr. Iacopo Baussano projected the burden of HPV-associated diseases using invasive cervical cancer (ICC) incidence as the show case of what HPV vaccination can deliver. Within the next 20 years, 250.000 extra annual cases (>50% increase), mostly in low and medium income countries (LMICs), will result due to the changes in demography, notably increasing life expectancy in LMIC. Ongoing transition of sexual behaviour patterns in the LMICs (male-dominated) towards that of the gender-similar sexual behaviour of the high income countries is rapidly increasing the occurrence of HPV type 16 in females and will eventually increase that of ICC incidence in the LMICs.

Based on a dynamic transmission model, the potential of early implementation of HPV vaccination at the start of the behaviour transition would result in, at least, 20 years earlier control of the HPV16/ICC epidemic than after the transition.

In addition to the HPV16/ICC epidemics, unexpected changes in the coverage of national HPV vaccination programs (such as the temporary reduction of the coverage rates in Japan from a coverage rate of 70% to a below 5% rate) may threaten their impact also by delaying the impact on the incidence in the high income countries. Based on the IARC model, which has been validated with Swedish population-based data on vaccinated birth cohorts, dr. Baussano described the resilience of the HPV vaccination programs to abrupt impaired coverage now a reality, e.g. in Japan due to the crisis created with inaccurate information of the safety of HPV vaccination [1].

Compared to a girls-only vaccination program the gender-neutral vaccination program with or without catch-up vaccination to age 18 were seven to thirteen times as resilient to the assumed crisis (figure 1) [2].

Gender-neutral scenarios reported in the Panel A assume routine vaccination of boys. Gender-neutral scenarios reported in the Panel B assume routine and extended catch-up (i.e. up to 26 years of age) vaccination of boys.
Shaded areas represent the resilience (i.e. the difference in prevalence relative reduction %) estimated with and without temporary coverage reduction. Estimated resilience with gender-neutral vaccination was 7 and 13-fold higher than with girls-only vaccination, with and without boys extended catch-up, respectively. Reproduced with permission [2].

Figure 1. Estimates of relative HPV16/18 prevalence reduction over time assume girls-only (pink) and gender-neutral (light blue) HPV vaccination with full (solid line) or impaired (dashed line) coverage

References
1. Hanley SJ, Yoshioka E, Ito Y, Kishi R. HPV vaccination crisis in Japan. Lancet, 2015. 385: p.2571.
2. Elfström KM, Baussano I, Lazzarato F, Franceschi S, et al. Human papillomavirus vaccination of boys and extended catch-up vaccination: Effects on the resilience of programs. J Infect Dis, 2016. 213:p.195-205.

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Iacopo Baussano, MD, PhD
Division of Infections and Cancer,
International Agency for Reserch on Cancer, Lyon, France
BaussanoI@iarc.fr

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