Information from FDA and CDC on Gardasil and its Safety (Archived)
July 22, 2008
Consumers, parents, healthcare professionals, and others have raised questions regarding the safety of the human papillomavirus (HPV) vaccine, Gardasil. FDA and CDC take all concerns about vaccine safety very seriously, and have been closely monitoring the safety of Gardasil.
Below is a summary of Gardasil vaccine safety monitoring activities and findings. Based on ongoing assessment of vaccine safety information, FDA and CDC continue to find that Gardasil is a safe and effective vaccine. FDA and CDC continue to monitor the safety of this vaccine with the public's health and safety our top priority.
FDA approved Gardasil vaccine on June 8, 2006 for use in girls and women through 26 years of age. This vaccine prevents infection with the types of HPV that cause most cases of cervical cancer and genital warts. CDC's Advisory Committee on Immunization Practices (ACIP) recommend routine 3-dose vaccination of girls aged 11 and 12 years. The vaccine is also recommended for girls and women ages 13 through 26 years who have not yet been vaccinated or who have not received all 3 doses.
Gardasil was tested in over 11,000 women in the United States and around the world, and found to be safe and effective in preventing serious HPV-related diseases. These studies showed that in women who have never been infected by HPV types 6, 11, 16, or 18, the vaccine is highly effective, both in preventing precancerous lesions that often develop into cancer of the cervix, vagina, and vulva, and in preventing genital warts often caused by these HPV types.
This vaccine is an important cervical cancer prevention tool that will potentially benefit the health of millions of women. Every year, about 12,000 women are diagnosed with cervical cancer and almost 4,000 die from this disease in the United States. Worldwide, cervical cancer is the second most common cancer in women, causing an estimated 470,000 new cases and 233,000 deaths per year.
Vaccine Safety Overview
FDA and CDC closely monitor the safety of all vaccines through the Vaccine Adverse Event Reporting System (VAERS). VAERS receives unconfirmed reports of possible side effects following the use of Gardasil and all vaccines licensed in the U.S. VAERS reports are regularly reviewed for safety concerns or trends of adverse events (possible side effects).
Vaccines are manufactured in batches called lots. All vaccine lots are routinely tested and must pass all tests before they can be used, and vaccine manufacturers must comply with strict manufacturing standards. FDA also analyzes adverse events (possible side effects) associated with individual lots to look for any unusual patterns. No such patterns have been observed in FDA's review of HPV vaccine lots since the vaccine was licensed.
In addition to VAERS, CDC has two other systems in place to monitor the safety of all licensed vaccines. The Vaccine Safety Datalink (VSD) Project is a collaborative effort between CDC and eight managed care organizations that monitors vaccine safety and immunization. The Clinical Immunization Safety Assessment (CISA) Network is a collaboration with six academic centers in the United States to conduct clinical research on vaccine-associated adverse events.
Adverse Event Reports Following Gardasil
To date, the manufacturer, Merck and Co., has distributed over 16 million doses of Gardasil in the United States. Given the large number of doses distributed, it is expected that by chance alone, serious adverse events and some deaths will be reported in this large population during the time period following vaccinations. Our monitoring and analysis of reports, including in depth medical review, are designed to detect serious events that occur at rates greater than expected, compared to what would be expected by chance alone.
VAERS receives reports of many events that occur following immunization. Some of these events may occur coincidentally during the time period following vaccination, while others may actually be caused by vaccination. In our analysis of VAERS data, we look for patterns of adverse events that may be plausibly linked to a vaccine. Such patterns of adverse events may require further study.
As of June 30, 2008, there have been 9,749 VAERS reports of adverse events following Gardasil vaccination. Of these, 94% were classified as reports of non-serious events, and 6% as serious events.
Non-serious Reports (94% of Total Reports)
Since Gardasil was approved, the great majority (94%) of adverse events reported to VAERS after receiving this vaccine have not been serious. These reports include syncope (fainting), pain at the injection site, headache, nausea, and fever. Fainting is common after injections and vaccinations, especially among adolescents. Falls after syncope may sometimes cause serious injuries such as head injuries, which can be prevented with simple steps, such as keeping the vaccinated person seated for up to 15 minutes after vaccination. FDA and CDC have taken steps to remind immunization providers about the recommendation that individuals be watched carefully for 15 minutes after vaccination to avoid potential injury from a fall. The vaccine's prescribing information has changed to include this information.
Serious Reports (6% of Total Reports)
Concerns have been raised about reports of deaths occurring in individuals after receiving Gardasil. As of June 30, 2008, 20 deaths had been reported to VAERS. There was not a common pattern to the deaths that would suggest they were caused by the vaccine. In cases where autopsy, death certificate and medical records were available, the cause of death was explained by factors other than the vaccine.
Guillain-Barré Syndrome (GBS) has also been reported in individuals following vaccination with Gardasil. GBS is a rare neurological disorder that causes muscle weakness. It occurs spontaneously in unvaccinated individuals after a variety of specific infections. FDA and CDC have reviewed the reports of GBS that have been submitted to VAERS. To date, there is no evidence that Gardasil has has increased the rate of GBS above that expected in the population. While we continue to carefully analyze all reports of GBS submitted to VAERS, the data do not currently suggest an association between Gardasil and GBS.
Thromboembolic disorders (blood clots) have been reported to VAERS in people who have received Gardasil. Most of these individuals had risk factors for blood clots, such as use of oral contraceptives which are known to increase the risk of clotting. Thromboembolic disorders as well as other medical events are being studied through the VSD in previously planned controlled studies. The manufacturer has also committed to conduct a large postmarketing study to further assess the vaccine's safety.
Based on the review of available information by FDA and CDC, Gardasil continues to be safe and effective, and its benefits continue to outweigh its risks.
CDC has not changed its recommendations for use of Gardasil. FDA has not made any changes to the prescribing information for how the vaccine is used or to the vaccine's Precautions. In addition, FDA routinely reviews manufacturing information and has not identified any issues affecting the safety, purity, and potency of Gardasil.
Public health and safety are priorities for FDA and CDC. As with all licensed vaccines, we will continue to closely monitor the safety of Gardasil. FDA and CDC continue to find that Gardasil is a safe and effective vaccine that will potentially benefit the health of millions of women by providing protection against the types of HPV that cause the majority of cervical cancer, genital warts, and other HPV-related diseases.