Needles are scary. But so are
sexually transmitted diseases (STDs), and if getting a
jab means not getting an STD, just about everyone
will be all for it. So the development of a vaccine that
prevents genital warts and, more importantly, cervical
cancer, will likely have even the most needle-phobic women
heading to the doctor.
The injection in question is a
vaccine for the two most common human papillomaviruses
(HPVs). The bivalent vaccine includes L1 virus-like
particles that resemble the outer shell of both HPVs
16 and 18, which account for 70% of HPV infections worldwide.
The results of a trial investigating the effectiveness
of the vaccine appear in the November 13 issue of The
Lancet.
For the study, 1,113 women between
the ages of 15 and 25 were tested for HPV 16/18, and
either vaccinated or given a placebo on three occasions
over an 18-month period. A sensitive genetic test that
amplifies tiny amounts of DNA was used to test for infection
during this time. In general, the vaccine was found
to be safe, well tolerated and showed high immunogenicity.
Women in the control group caught HPV and had persistent
infection at a rate close to that of the general population.
In stark contrast, the vaccination group escaped persistent
infection with this STD — not one case was detected
— and had one-tenth the normal rate of catching
it in the first place.
Overall, the vaccine prevented
initial HPV infection 92% of the time and was 100% effective
in protecting against persistent infections. Even more
importantly, it also prevented the cytological abnormalities
and lesions that are hallmark indicators of the early
stages of cervical cancer. Lead researcher
Dr Diane M Harper of Dartmouth
Medical School in New Hampshire called the results "extremely
exciting and encouraging. We believe this shows enormous
potential to eradicate the great majority of cervical
cancers worldwide."
Rx
FOR ROUTINE SHOTS
A much larger trial, the final testing phase before
this vaccine can be licensed for general use, is set
to begin. As such, HPV vaccination may soon be routine
for young women. If the vaccine proves successful, it
would save billions in cancer treatment costs, and save
thousands of lives. As Dr Harper suggests, "a prophylactic
vaccine program, directed at young adolescent women,
is likely to be cost-effective in both screened and
unscreened populations, with important long-term implications
for cervical cancer prevention."
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