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Study Examines Adverse Events Associated With HPV Vaccine

CHICAGO -- August 18, 2009 -- An analysis of the adverse events reported
following distribution of quadrivalent human papillomavirus recombinant
vaccine (qHPV) since 2006 indicates that adverse event rates were consistent
with pre-licensing data and expected background rates of other vaccines,
with the exception of a higher proportion of reports of fainting and blood
clots, according to a study published in the August 19 issue of JAMA.

In June 2006 the US Food and Drug Administration (FDA) licensed the qHPV for
females aged 9 to 26 years to prevent infection with genital human
papillomavirus (HPV) types 6, 11, 16, and 18. Shortly after that, the
Advisory Committee on Immunization Practices (ACIP) recommended routine
vaccination of females aged 11 to 12 years with 3 doses of qHPV and catch-up
vaccination for females aged 13 to 26 years.

Prior to licensing, clinical trials were conducted with more than 21,000
women. The incidence of clinical adverse events following immunisation
(AEFIs) was similar in the vaccine group (59%) and the placebo group (60%),
and the rates of serious AEFIs were comparable between the 2 groups (< 0.1%)

Barbara A. Slade, MD, Centers for Disease Control and Prevention, Atlanta,
Georgia, and colleagues analysed reports of adverse events following qHPV
immunisation received by the US Vaccine Adverse Event Reporting System
(VAERS) from June 1, 2006, through December 31, 2008. Additional analyses
were performed for some AEFIs in prelicensure trials, those of unusual
severity, or those that had received public attention.

During the study period, VAERS received 12,424 reports of AEFIs following
receipt of qHPV, an overall reporting rate of 53.9 reports per 100,000
vaccine doses distributed. Of the 8,247 reports that included onset interval
 4,393 (40%) occurred on the day of vaccination. Among 9,396 reports (77%)
with dose information, 5,772 (61%) followed the first dose, 2,380 (25%)
followed the second dose and 1,183 (13%) followed the third dose of qHPV.

Among the 12,424 AEFI reports, 772 (6.2%) were serious, including 32 reports
of death. The reporting rates per 100,000 qHPV doses distributed were 8.2
for syncope; 7.5 for local site reactions; 6.8 for dizziness; 5.0 for nausea
 4.1 for headache; 3.1 for hypersensitivity reactions; 2.6 for urticaria; 0
2 for venous thromboembolic events, autoimmune disorders, and Guillain-Barré
syndrome; and 0.1 for anaphylaxis and death. Analysis indicated a
disproportional reporting of fainting and blood clot events.

"The postlicensure safety profile presented here is broadly consistent with
safety data from prelicensure trials," the authors wrote. "Because VAERS
data must be interpreted cautiously and cannot generally be used to infer
causal associations between vaccines and AEFIs, postlicensure monitoring
will continue, and identified signals may be evaluated using epidemiologic
observational studies."