Where HPV vaccination loses the battle for public support: calculating the health implications for Japan

A recent brief contribution to The Lancet-Oncology (Tanaka & Ueda) uses predictions of the probable health outcomes of the suspension of the Japanese HPV vaccination programme to make the case for an urgent reassessment of the current policy.  This intervention is very timely.  The approved age for HPV vaccination for Japanese girls is a window of four years from 13-16 yrs, and the current year (2016-17) constitutes the fourth since the suspension of the programme (June 2013); so the current year is the last opportunity for a return to the initial HPV vaccination policy before the effects of the suspension (for the oldest in the cohort) become irrevocable.   From the following year on (2017-8), the authors argue, every additional year of suspension will exclude an additional age group from the protective effects of HPV vaccination – unless, that is, the eligibility period is extended to include older girls).  With a view to maximizing the impact of this message, they assess the impact of restarting vaccination in 2020 as against restarting in the current year.  They do this on two scenarios depending on whether or not vaccination, when resumed, is given to those who would have missed out in 2013-2017 as well as to those currently eligible.

So how great are these effects?   On the first scenario (no catch-up for missed years), risk of HPV 16/18 infection at 20yrs is estimated for the 2013-6 year groups at around a steady 1.0%, given resumption of vaccination 2020, as against the 0.3-0.4% risk, with resumption in 2016; on the second, that steady 1% risk over the four missed years is replaced by an evenly paced decline from 1.0% to previous levels (0.3-0.4%) over the four-year period.

Of course, it is the long-term health impact of these HPV infections that constitutes the cost of the current Japanese policy, and, were it recognized, the strongest incentive for a resumption of vaccination.  Unfortunately, the full impact is very long term, and hard to quantify.  But some advanced indication of its potential scale is provided by the recent Finish ‘FUTURE’ trial that demonstrated an absence of CIN3 and ICC lesions in vaccinated participants (Paavonen/3/STIs), as well as, more indirectly, the enormous (c.90%) declines in genital wart presentations in Australia (Chow & Fairley/STIs; Ali & Donovan (STIs)) and New  Zealand (Wilson & Baker/STIs).  The benefits foregone by the unvaccinated will also include protection against head and neck – especially oropharyngeal – cancers (Field & Lechner/STIs; King & Sonnenberg/STIs), and against a small, but significant range of anogenital cancers in women (Prevention of anogenital cancers in women/STIs/blogs).  On a more positive note, however, there is some evidence for the benefit of ‘catch-up’ and incomplete vaccination (“Catch-up” and incomplete vaccination/STIs/blogs) as against those who have hitherto put this in doubt (STs/Chesson & Markowitz).

An important lesson of the Japanese experience for everyone concerned with HPV is the importance of public education.  The very poor levels of understanding revealed by a recent systematic review (Patel & Moss/STIs) amongst European adolescents is a timely warning that uninformed attitudes to HPV vaccination are not restricted to the Japanese.