HIV-positive girls did not
respond as well to the quadrivalent human papillomavirus (HPV) vaccine as
HIV-negative girls of the same age, but they responded as well as HIV-negative
older women, probably giving them sufficient protection from infection, according
to a late-breaker presentation at the IDWeek 2013 conference recently held in San
Human papillomavirus can
trigger abnormal cell proliferation and cause warts, tissue abnormalities
(dysplasia or neoplasia) and malignancies including cervical and anal cancer.
Two effective HPV vaccines
are available. The bivalent Cervarix vaccine protects against cancer-causing
HPV types 16 and 18. The quadrivalent Gardasil vaccine protects against 16 and
18 as well as wart-causing types 6 and 11. HPV vaccines are recommended for
girls and boys aged nine through to their mid-twenties. Most people become infected
with HPV soon after they become sexually active, so vaccination is recommended
People with HIV who have
substantial immune system damage may not produce as many antibodies in response
to vaccination, but this has not been extensively studied in relation to HPV.
It is an important issue because HIV-positive women and men have higher rates
of HPV infection, dysplasia and cervical and anal cancer.
Money from the University of British Columbia conducted a study to test the efficacy of
a HPV virus-like particle quadrivalent vaccine in HIV-positive girls and women.
Among HIV-negative people,
HPV vaccination is most effective for adolescents aged 9 to 13 and more than
99% of females and males achieve adequate antibodies after the standard three
doses, the researchers noted as background.
multicentre study included 407 HIV-positive female adolescents enrolled at eleven
sites in Canada between November 2008 and December 2012. Almost all were
exposed to HIV through mother-to-child transmission. Most participants were in
the 9 to 13 age group (mean 11 years) but 27 were younger; a majority had not
yet started menstruation. Most (70%) were African-Canadian, 4% were white and
26% were 'other'.
participants had undetectable HIV viral load at baseline. The mean baseline CD4 cell count was 710 cells/mm3 and the nadir (lowest-ever) level was
470 cells/mm3, indicating well-preserved immune function. All but
one tested negative for the four HPV types in the vaccine (6, 11, 16 and 18) at
comparison group included 825 girls and women ages 9 to 13 or 16 to 26 in
another study comparing two versus three doses of the vaccine. In that study
most participants (80%) were white and 18% were Asian.
HIV-positive girls received three vaccine doses, one at study entry with
boosters at two and six months later; follow-up continued for two years.
HIV-positive girls in the study completed the full vaccine schedule and all
experienced seroconversion, or production of antibodies against all HPV types
in the vaccine. The overall response rate for the entire cohort was 99%.
Girls with HIV
viral suppression achieved two- to three-fold higher antibody titres than those
with unsuppressed HIV, but there were few girls in the latter group and
differences did not reach statistical significance. There were no differences
in response according to baseline or nadir CD4 count.
HIV-positive girls had significantly lower geometric mean antibody titres (GMT)
than HIV-negative girls aged 9 to 13 in the comparison study for all four HPV
types in the vaccine at months 7 and 24. Looking at the older HIV-negative
women (ages 16 to 26), however, antibody levels were similar and difference were
not significant for any HPV type.
quadrivalent vaccine was safe and well tolerated by HIV-positive girls. No
serious adverse events considered related to the vaccine were reported.
In this study there was a "high rate of
seroconversion seen in HIV-positive girls given the quadrivalent HPV vaccine by
standard dosing", the researchers concluded. "Lower peak GMT was
observed in these HIV-positive girls compared to HIV-negative girls."
However, they continued, "levels of
response were comparable to levels seen in older women for whom data is
available[, suggesting] that these levels confer efficacy against HPV infection and disease".
They cautioned that "until an immune
correlate of protection is defined in HIV-negative and HIV-positive persons,
understanding of the meaning of antibody levels remains limited", and
"the role of booster dosing remains to be evaluated".
Although this study looked only at HIV-positive
girls, the trend in HPV vaccine research over the past several years has been
that similar results are seen in boys and men.