June 09, 2016
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Decade of Gardasil vaccination reduces global infection, anogenital warts, cervical lesions

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A recently published literature review suggested that global uptake of Gardasil quadrivalent HPV vaccine has led to a major reduction in infection rates, as well as fewer reports of several related conditions.

HPV incidence declined nearly 90% in regions with higher population coverage, but lagged among those with lower uptake, according to Suzanne M. Garland, MBBS, MD, director of the women’s center for infectious diseases at the University of Melbourne’s Royal Women’s Hospital, and colleagues. They said this highlights the need for increased vaccination coverage among lower income countries and difficult-to-reach populations.

“Over 205 million doses of [Gardasil, Merck; (4vHPV)] vaccine had been distributed worldwide as of Dec. 31, 2015,” the researchers wrote. “Although high efficacy against multiple endpoints was consistently observed in clinical trials, it is essential to document how trial results translate to real-world settings.”

To do this, Garland and colleagues assessed peer-reviewed data published from 2007 through February. They included observational studies examining the impact of 4vHPV vaccination on infection and related diseases, and excluded those describing the bivalent vaccine, review papers, simulations and data reviews. The final analysis included 58 publications reporting vaccination’s impact on HPV infection and related conditions for nine countries.

The data indicated consistent decreases in HPV 6/11/16/18 cervical or vaginal infections, anogenital warts, low- and high-grade cytological abnormalities, high-grade cervical intraepithelial neoplasia and adenocarcinoma in situ within targeted female populations after introduction of the vaccine. Declines were greatest among younger birth cohorts and were detected as early as 2 years to 4 years after vaccine introduction across all settings. The effectiveness and impact of vaccination within a country was dependent on several factors, including coverage, age of target cohort, implementation and duration of a catch-up program.

Garland and colleagues found reductions of approximately 90% for HPV infection, genital warts and high-grade histologically proven cervical abnormalities, as well as an approximately 60% reduction in low-grade cytological cervical abnormalities among countries with the greatest vaccine coverage. However, the reduced impact among countries with less coverage, or among countries not included in the review whose vaccination programs may not be fully developed, suggests areas in need of improvement.

“Preventable HPV-related diseases persist, underscoring the need for wide-reaching HPV vaccination programs with high population coverage prior to HPV exposure,” the researchers wrote. “Universal adoption of safe and effective prophylactic HPV vaccine programs targeting girls and boys before sexual debut can prevent the substantial morbidity and mortality still attributable to HPV worldwide. Ensuring broad coverage of appropriate populations can provide a major advancement in global public health.” – by Dave Muoio

Disclosure: Garland reports relationships with GlaxoSmithKline and Merck, receipt of honoraria for lectures and is a co-chair of the PATRICIA publication steering committee. Please see the full study for a list of all other authors’ relevant financial disclosures.