Wednesday, September 24, 2008
News Author: Laurie Barclay,
CME Author: Yael Waknine
September 18, 2008 — The US Food and Drug Administration (FDA) announced yesterday that approval for the vaccine Gardasil (HPV quadrivalent [types 6, 11, 16, and 18] recombinant vaccine) has been expanded to include the indication of preventing vaginal and vulvar cancer caused by human papillomavirus (HPV) types 16 and 18 in girls and women aged 9 to 26 years.
"There is now strong evidence showing that this vaccine can help prevent vulvar and vaginal cancers due to the same viruses for which it also helps protect against cervical cancer," Jesse L. Goodman, MD, MPH, director of the FDA's Center for Biologics Evaluation and Research, said in a news release. "While vulvar and vaginal cancers are rare, the opportunity to help prevent them is potentially an important additional benefit from immunization against HPV."
In 2006, the original FDA approval for Gardasil was for the prevention of cervical cancer caused by HPV types 16 and 18, which cause 70% of cervical cancers and which are implicated in unknown percentages of vulvar and vaginal cancers. The original approval, which was for girls and women aged 9 to 26 years, was also for the indications of preventing precancerous genital lesions caused by HPV types 6, 11, 16, and 18 and genital warts caused by HPV types 6 and 11.
In the United States, HPV is the most prevalent sexually transmitted disease, with an annual incidence of 6.2 million new infections, according to the US Centers for Disease Control and Prevention.
Merck & Co Inc, the manufacturer of Gardasil, followed up on more than 15,000 participants from the original cervical cancer prevention studies for 2 more years to determine the effects of Gardasil on the risk for vulvar and vaginal cancer compared with control participants who had not received Gardasil.
This follow-up showed that Gardasil was highly effective in preventing HPV-related precancerous vulvar and vaginal lesions in women who tested negative for HPV types 16 or 18 at study enrollment. None of the participants in the Gardasil group developed HPV type 16- or 18-related precancerous lesions compared with control group findings of 10 precancerous vulvar lesions and 9 precancerous vaginal lesions related to HPV types 16 or 18.
Women previously infected with HPV types 16 or 18 before immunization had no evidence of benefit. To optimize the preventive effects of Gardasil, the investigators therefore recommend vaccination before potential exposure to HPV types 16 or 18.
Caveats from the FDA represented in the label are that presently available information is insufficient to support use in women older than age 26 years and that Gardasil does not protect against diseases caused by other HPV types. Because Gardasil does not protect against preexisting HPV infections and because no vaccine is 100% effective, all women should continue to be monitored with Papanicolaou tests, even after vaccination.
Most adverse events of Gardasil reported since FDA approval in 2006 have not been serious. The most frequently reported adverse events have included syncope, injection site pain, headache, nausea, and fever. Observation is recommended after vaccination in case of syncope or severe allergic reactions.
A short- and long-term safety surveillance study is underway of 44,000 individuals in a managed care organization who received Gardasil for all its approved uses.
Source :Gardasil Prescribing Information
The FDA has approved an expanded indication for a quadrivalent recombinant vaccine, allowing its use for the prophylaxis of vaginal and vulvar cancer caused by HPV types 16 and 18 in girls and women aged 9 to 26 years.
The HPV vaccine is administered as an intramuscular injection at 0, 2, and 6 months.
Previously, the FDA approved use of the vaccine for the prevention of cervical cancer caused by HPV types 16 and 18; precancerous genital lesions caused by HPV types 6, 11, 16, and 18; and genital warts caused by HPV types 6 and 11.
The current approval was based on data from 3 placebo-controlled, randomized studies that followed up on 18,714 participants for a mean of 3 years; approximately 50% had been vaccinated.
Results showed that the vaccine was 100% effective for preventing precancerous high-grade vulval intraepithelial neoplasia and vaginal intraepithelial neoplasia caused by HPV types 16 and 18 in girls and women who tested negative for infection up to 1 month after the last dose.
In the intent-to-treat population, which included all participants, the vaccine was 71% effective against vulvar intraepithelial neoplasia or vaginal intraepithelial neoplasia associated with HPV 16 or 18.
Results also showed the vaccine to be 49% effective against all vulvar intraepithelial neoplasia or vaginal intraepithelial neoplasia irrespective of whether HPV DNA was detected in the lesion.
No evidence of vaccination benefit was observed in girls and women previously infected with the HPV subtypes contained in the vaccine.
There is insufficient evidence to support use of the vaccine in women older than 26 years.
Adverse events most commonly include syncope, pain at the injection site, headache, nausea, and fever. Because of the potential for allergic reactions and syncope, a 15-minute postvaccination observation period is recommended.
Pearls for Practice
The FDA has approved an expanded indication for HPV quadrivalent (types 6, 11, 16, and 18) recombinant vaccine, allowing its use for the prevention of grades 2 and 3 vulvar and vaginal intraepithelial neoplasia caused by HPV types 16 and 18 in girls and women aged 9 to 26 years. Clinical data showed 100% efficacy in women who were infection naive at baseline. Intent-to-treat efficacy was 71%.
No evidence of benefit was observed in girls previously infected with the HPV subtypes contained in the vaccine, and there is insufficient evidence to support its use in women older than 26 years. Because of the potential for allergic reactions and syncope, patients should be observed for 15 minutes after vaccination.
Sunday, September 14, 2008
California Data Do Not Support a Link Between Thimerosal in Vaccines and
Continuing Increases in Autism Reported to California's Developmental Services System: Mercury in Retrograde
Schechter R, Grether JK
Arch Gen Psychiatry. 2008;65:19-24
This study was a retrospective review of autism spectrum disorder (ASD) cases referred to the California Department of Developmental Services (DDS) from 1995 through 2007. Children enter the DDS system at 3 years old; therefore, this referral represents the prevalence of a diagnosis of ASD in this population at the age of 3 years.
The authors plotted the prevalence of ASD referrals against critical time points in US vaccine history relative to the use of thimerosal. Critical dates relative to thimerosal are:
The authors' hypothesis was that if thimerosal were a contributor to ASD then children born and vaccinated after 2002 should have decreased rates of ASD diagnosis, and this would be reflected in decreased numbers of referrals (ie, decreased prevalence) to California DDS.
The authors did not find a dip in referral rates; their data did not reflect a change in ASD prevalence. In fact, the prevalence of ASD was increasing before 1991 and continued on roughly the same slope throughout the 1990s and 2000s, regardless of age group evaluated.
Only one year's cohort of children was born after thimerosal was largely eliminated from vaccines and were not at risk for receiving old vaccine -- the children born in 2003. These children also had a higher prevalence of ASD than children born in previous years, and the slope was increasing along a very similar trajectory to prior years. The increase over the time period 1993 through 2003 was from 0.3 cases per 1000 births to 1.3 cases per 1000 births.
The authors conclude that the California DDS data do not support a link between thimerosal in childhood vaccines and development of ASD.
This study was published in January 2008 but only recently came to my attention. The findings here mirror those of a Danish study that demonstrated ongoing increases in ASD diagnosis despite removal of thimerosal from vaccines, as well as Canadian data demonstrating no decrease in ASD diagnosis for children vaccinated with non-thimerosal-containing vaccines. The figure from the Canadian study is particularly interesting and is worth viewing separately.