Feature
Understanding the new HPV vaccine: What GPs need to know
Public health physician Associate Professor Julia Brotherton writes for newsGP about Australia’s new nonavalent HPV vaccine.
The new two-dose nonavalent HPV vaccine replaces the three-dose quadrivalent vaccine.
Australia has introduced the nonavalent human papillomavirus (HPV) vaccine (brand name Gardasil 9) in a routine two-dose schedule into the National Immunisation Program (NIP), replacing the three-dose quadrivalent vaccine (brand name Gardasil).
This month will see parents of girls and boys aged 12–13 considering whether to consent to their child receiving the vaccine in the school-based program. In addition, catch-up HPV vaccination has been funded through the NIP for those aged up to 19 since July 2017.
Here is some of the information GPs need to know about the new vaccine.
The new vaccine extends protection against cancer-causing HPV types
Gardasil 9 contains the same virus-like particles as the quadrivalent vaccine (types 6 and 11, which cause genital warts, and types 16 and 18, the two most oncogenic) with the addition of five oncogenic HPV types, which are the next most frequently detected in cervical cancers (types 31, 33, 45, 52 and 58).
This will increase the level of protection against cervical cancer in Australia from over 70% to over 90%, and also increase the level of protection against high-grade cervical lesions. There is a much smaller additional benefit in protection against other HPV related cancers, as the vast majority of these are caused by HPV types 16 and 18.
The vaccine works very well and is very safe
Randomised trials
have demonstrated that the vaccine has 97% efficacy against infection and high-grade disease due HPV types 31, 33, 45, 52 and 58 when given to women who are not already infected. Antibody responses against types 6, 11, 16 and 18 are equivalent to those produced after quadrivalent vaccination.
The new vaccine is manufactured in the same way as the quadrivalent vaccine, with a greater amount of adjuvant and virus-like particles for types 16, 18 and 6 in order to maintain robust immune response against these types.
The incidence of injection-site reactions is slightly higher than with quadrivalent vaccine, although local reactions occur less frequently in girls and boys than in adult women. There is no difference in the incidence of systemic adverse events between the vaccines.
HPV vaccines have been used globally for more than a decade in over 270 million doses, and the World Health Organization (WHO) continues to find them safe for population use.
Two doses are now recommended for those aged 14 and under
Data
now support the routine use of two doses of HPV vaccine delivered 6–12 months apart in people aged 14 and under at first dose, with three doses still required in older individuals or in those with significant immunocompromise (refer to the
Australian Immunisation Handbook for details).
Age at first dose determines eligibility for two doses. Spacing is important, with a longer interval required between the doses (no shorter than six months). Note that the program now routinely funds two doses of HPV vaccine rather than three, except in the case of those with immunocompromise.
HPV vaccines are interchangeable and previous doses do not need to be re-administered
Recipients of incomplete courses who commenced with quadrivalent or bivalent vaccine can complete the course with nonavalent vaccine. Interrupted courses never need to be restarted.
For those who have previously received two doses, only those who were 14 or under at the time of their first dose and whose two doses are spaced six months or more apart are now considered complete. All other recipients should complete the three-dose course.
Revaccination with the new vaccine is not routinely recommended for those previously vaccinated
This is because the most significant benefit of HPV vaccine is protection against the most oncogenic types HPV 16 and 18. All three HPV vaccines provide excellent protection against these types.
Recent research
suggests that 50% of HPV infections that will ever cause cervical cancer have been acquired by the age of 20, and 75% by age 30. Cervical screening is the most important additional preventive action sexually active women can undertake.
Individual patients who have previously been HPV-vaccinated may choose to receive a second course using nonavalent HPV vaccine (this is not funded under the NIP). Three doses are required for anyone commencing the course at age 15 or older. There may be an increase in the likelihood of significant local injection site reactions in this group.
Revaccinated women also produce lower antibody titres to the five additional HPV types than
HPV-vaccine naïve women, but the clinical significance of this finding, if any, is unknown.
Further resources
Visit the National HPV Vaccination Program Register
website for more information and links, including provider and patient infographics about the new vaccine.
HPV-Vaccination-Program HPV-vaccine nonavalent-HPV-vaccine
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