HPV Vaccination over 19 years, why not?
Feb 03, 2023
Australia has led the way in fight against cervix cancer by being the first country in the world to introduce a national HPV vaccination program, and to include vaccination for boys as well.
Cervical cancer commonly affects women of reproductive age group. Cervical precancer (cervical intraepithelial neoplasia) is typically diagnosed in women of reproductive age
group. Even though eminently treatable in the form of cervical conisation or loop excisional procedures, there is a small but credible risk of affecting future childbearing by increasing the risk of premature birth in any subsequent pregnancies.
We also prepare ourselves to align with the World Health Organisation’s (WHO) Cervical Cancer Elimination Strategy of a cervical cancer incidence of less than 4 per 100,000, a goal that is conceivably achievable in Australia well ahead of the WHO timeline given the low incidence of cervical cancer in our population.
Australia is a large country with a small population, a significant proportion of whom may have been brought up in a different country and may not have had access to HPV vaccination. Additionally, even in Australia a fifth of children in high school fail to complete HPV vaccination. A small number from these children may have received single dose of the vaccine. Girls tend to fare better than boys in having received both or one dose of HPV vaccine.Gardasil 9® is the current vaccine being administered under the National Immunisation Program (NIP). Gardasil® (quadrivalent) and Cervarix® (bivalent) were used in the initial phase of the vaccination program and continue to be available in Australia.
It is recommended that both boys and girls are vaccinated with two doses of Gardasil 9® by the age of 15 years. However, they can be vaccinated up to 19 years of age under NIP. For women who have not previously engaged with primary health care, the time of first Cervical Screening Test, at 25 years of age under the new screening guidelines, may be an opportune time to enquire into and discuss HPV vaccination.
In gynaecological practice the question of prior HPV vaccination arises once a woman has already been diagnosed with or referred with an abnormal Cervical Screening Test (CST). Following are some of the common queries related to HPV vaccination.
The following discourse refers to low risk population. Unvaccinated women who present with immune deficiency syndromes, autoimmune disease, organ transplant should be considered for HPV regardless of age at presentation.
What is the role of HPV vaccination in someone with abnormal cervical screening or cervix dysplasia?
HPV infection of the cervix does not cause viraemia and hence does not induce humoral immunity. Women diagnosed with dysplastic changes in the cervix have already demonstrated the failure of the local immune system to eliminate HPV from the genital tract.
HPV vaccination in this situation is not aimed at elimination of existing infection or reversal of dysplastic changes. The aim of the vaccination in this group is to reduce the future risk of HPV infection with a different strain of HPV.
How long should I wait before prescribing HPV vaccine after diagnosis/treatment of cervical dysplasia?
Previously unvaccinated adults are more likely to engage with the health professionals and consider vaccination related advice when diagnosed with an abnormal cervical screening or dysplasia of the cervix.
HPV vaccination should be discussed with all unvaccinated women with abnormal cervical screening. There is no need to wait for a negative HPV test prior to offering vaccination.
The woman in a stable relationship, should I still offer the vaccine?
The risk of new HPV infection is higher if new sexual partners are expected, and health care professionals are more likely to recommend HPV vaccination in adults in this scenario. The efficacy of the vaccine, and hence the benefit from vaccination, in an adult woman currently in a monogamous relationship is low.
However, I feel that it is our responsibility to provide information on the availability of the vaccine to the woman who has presented with cervical dysplasia regardless of the relationship status. The side effects of HPV vaccination are low, although we do need to factor in the cost of vaccination. The vaccine is licenced for use up to the age of 45 years.
My patient is enquiring into repeat vaccination with the newer vaccine.
It is correct that the current HPV vaccine on the NIP schedule, Gardasil 9®, covers 7 cancer causing HPV strains but incremental benefit of protection from additional strains in the current vaccine is small. The additional 5 strains of HPV included in the newer vaccine collectively only account for additional 15% to 20% of cervix cancers. The risk of local side effects from at the injection site are higher in women receiving a fresh course of HPV vaccines after having completed vaccination previously.
Are there any additional benefits to HPV vaccination in adults?
We need to look beyond cervix cancer when considering HPV vaccination in adults. Vaccination is likely to offer varying degrees of protection against vulval, oral, anal and penile HPV infection and HPV related disease. HPV vaccination has the potential to reduce the burden of morbidity from a wide spectrum of premalignant and malignant conditions.
Dr Vivek Arora
Gynaecologist and Gynacological Oncologist
325 Crown Street
P: 1300 971 265
F: 02 4226 6196