HPV Prevention
While male circumcision can cut the risk of HPV infection
in men by 30%
and in their wives by
23%, and
consistent condom use can cut the risk of HPV infection by
27%
to
70%,
the most effective intervention is vaccination.
Clinical trials show that vaccination against HPV effectively prevents
against the strains of HPV that cause about 70% of cervical cancer
(pubmed
21629249) and reduces high-grade cervical lesions (precursors to cancer)
(text, pubmed 17671238).
Consequently, HPV vaccination is now recommended by most national health organizations, including:
Vaccination campaigns have been underway since about 2007,
and efforts are underway to monitor their
safety and effectiveness:
- The HPV vaccine
impact monitoring project (HPV-IMPACT): assessing early evidence of
vaccination impact on HPV-associated cervical cancer precursor lesions (
pubmed 22108842
)
- Monitoring of human papillomavirus vaccination (
pubmed 21062269 )
- Report of the meeting on HPV Vaccine Coverage and Impact Monitoring (
text
)
- Approaches to monitoring biological outcomes for HPV (
pubmed 20971113
)
- Monitoring the control of human papillomavirus (HPV) infection and related diseases in Australia: towards a national HPV surveillance strategy (
text /
pubmed 20719220
)
- Post-licensure monitoring of HPV vaccine in the United States. (
text /
pubmed 20188681
)
Definitive evidence of actual cancer prevention is not expected until ten or twenty years
after the start of the public vaccination campaigns - about 2018 or 2028 -
but some health benefits will show up sooner.
Firstly, public campaigns using Gardasil already seem to be
effective against genital warts:
-
The near disappearance of genital warts in young women 4 years after commencing a national human papillomavirus (HPV) vaccination programme
(
paid text /
pubmed 21970896
) -
"of new patients attending Melbourne Sexual Health Centre... Comparing the two 12-month periods of 2007/2008 and 2010/2011, [genital warts] declined in women under 21 years from 18.6% to 1.9% and in heterosexual men under 21 years from 22.9% to 2.9%."
-
Impact of the human papillomavirus (HPV) vaccine on genital wart diagnoses at Auckland Sexual Health Services
(
pubmed 21952330
) -
"[In] clients under the age of 20 years, found genital warts in males
decreased from 11.5% in 2007 to 6.9% in 2010 while in females the rates
decreased from 13.7% to 5.1% over the same time period."
Second, there is already a little evidence that HPV immunization campaigns are effective at reducing abnormal pap smears (a precuror to cancer):
-
Early effect of the HPV vaccination programme on cervical abnormalities in Victoria, Australia: an ecological study
(
pubmed 31684381
)
- Statistical Report 2011, Victorian Cervical Cytology Registry (
text)
Figure 5.2 shows the rate of histologically-confirmed
high-grade cervical abnormalities over time, by age group.
The previously noted decline, following the National HPV
Vaccination Program, in women under 20 years of age is
continuing, with a halving of the rate of 14 cases per 1,000
women diagnosed in 2006 down to 7 cases per 1,000 in 2011.
Whilst rates in women 25+ years are steadily increasing,
rates in women 20 to 24 years appear to be declining away
from the underlying increasing trend and are diverging away
from the rates in 25 to 29 year old women. For the first time in
a decade, rates in 25 to 29 year old woman are clearly higher
than those in 20 to 24 year olds. These trends are suggestive
of the emerging effect of the HPV vaccine...
Finally, the vaccine won't do any good if people don't take it, so a number of
studies have been done on public acceptance of HPV vaccination; here is a small sampling.
-
Global challenges of implementing human papillomavirus vaccines (
text /
pubmed 21718495
)
- National and State Vaccination Coverage Among Adolescents Aged 13 Through 17 Years --- United States, 2010 (
text /
pubmed 21866084
)
- Explaining variation in the uptake of HPV vaccination in England (
text /
pubmed 21426539
)
- HPV vaccine acceptance, utilization and expected impacts in the U.S.: Where are we now? (
text /
pubmed 20855941
)
- A Population-Based Evaluation of a Publicly Funded, School-Based HPV Vaccine Program in British Columbia, Canada: Parental Factors Associated with HPV Vaccine Receipt (
text /
pubmed 20454567
)
-
Challenges and Opportunities for U.S. Family Planning Clinics in Providing the HPV Vaccine (
policy paper )
More about the qualms some parents have about HPV vaccination
here.
Merck is currently
studying a HPV vaccine ("V503") that protects against 9 strains of HPV
(HPV16, -18, -31, -33, -45, -52, -58, -6, and -11); it might become available in 2015.
(See Nov 4 2013 press release,
Oct 24 2013 press release)
Copyright 2011, 2012, 2013 Dan Kegel
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