CDC Commentary: New Safety Data on the HPV Vaccine -- Reassure Your Patients

Claudia Vellozzi, MD, MPH


June 14, 2010

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Hello. I'm Dr. Claudia Vellozzi. I'm a family practitioner and the deputy director of CDC's Immunization Safety Office. Our office, along with the Food and Drug Administration monitors the safety of vaccines after they are licensed.

Today, I'm pleased to share with you important safety data on the human papillomavirus, or HPV vaccine as part of the CDC Expert Commentary Series on Medscape.

As healthcare providers, we know that clear communication goes hand in hand with good quality patient care. Talking with your patients about the safety of HPV vaccines can help to address common concerns about vaccination and may lead your patients, or their parents, to make more informed decisions about their health.

Although there are 2 licensed HPV vaccines in use in the United States (Gardasil and Cervarix), we currently have more available data on Gardasil. As of January 1, 2010, 28 million doses of Gardasil have been distributed in the US.

CDC and FDA manage the Vaccine Adverse Event Reporting System (or VAERS), a system which accepts reports for any adverse event after vaccination from healthcare providers, patients, or family members, or manufacturers. VAERS is one of the systems that helps us to monitor the safety of vaccines in this country. It is a front-line system to detect possible safety concerns. VAERS has several limitations. It is always important to keep these in mind when you are reviewing VAERS data.

The main limitations are:

  • VAERS usually cannot assess causality;

  • VAERS has variable quality of data;

  • VAERS lacks denominator data (the total number of vaccinated persons is not known); and,

  • VAERS is subject to variable reporting (both underreporting and stimulated reporting can occur).

As of January 31, 2010, VAERS had received nearly 16,000 reports of adverse events following Gardasil vaccination. An overwhelming majority of these (over 90%) were non-serious, such as syncope (or fainting), local injection site reactions, dizziness, nausea, and headache. These findings are similar to the safety reviews of other vaccines recommended for a similar age group (such as meningitis and Tdap vaccines).

Based on the review of available vaccine safety monitoring data by FDA and CDC, HPV vaccination continues to be recommended and its benefits continue to outweigh its risks.

Now, let's talk about some of the serious adverse event reports. All serious reports were analyzed by medical experts and additional medical records were requested to better understand the adverse events. Some of the serious reports were reports of venous thrombotic events or VTE. In VAERS, most individuals who reported VTEs post-vaccination were also found to have other high risk conditions documented in their medical records, such as use of oral contraceptives, smoking, obesity, or other contributing factors.

All of the death reports in VAERS were fully investigated, and there was no unusual pattern or clustering that would suggest that they were caused by the HPV vaccine. The reported causes of death could be explained by factors including diabetes, viral illness, illicit drug use, and heart failure.

Like any medication, vaccines can have some side effects. After HPV vaccination, your patients may experience mild events such as local injection site reaction (including soreness, redness, or swelling where the shot was given), and some patients may be prone to syncope. Syncope after vaccination is not uncommon among adolescents and young adults. Be sure your patient is vaccinated while sitting or lying down and is observed for at least 15 minutes after vaccination to avoid potential injury from a fall in the event of syncope. If syncope does occur, observe your patient and evaluate them after they regain consciousness to determine if there is a need for further treatment. Fainting after vaccination itself is usually not a serious event, and patients generally recover within a few minutes.

Remember, one limitation of VAERS is that it cannot determine causality. A report to VAERS is only an association in time, meaning that the adverse event occurred some time after vaccination. CDC and FDA thoroughly investigate all serious reports to better assess whether more studies are needed to help determine if an adverse event could be associated with a vaccine. Although the media has paid particular attention to these adverse event reports, it is important to know and share with your patients that we have not found any information to conclude that these events were associated with the vaccine.

I would like to summarize with the following points:

First, based on the review of available information by FDA and CDC, the HPV vaccine continues to be recommended for girls and women, ages 9 to 26 years, as an important strategy to prevent cervical cancer. Gardasil can protect males against most genital warts and may be given to boys and men, ages 9 through 26 years.

Second, you should consider watching your patients carefully for 15 minutes after any vaccination, including administration of the HPV vaccine, to avoid potential injury from a fall in the event of syncope.

Third, discuss with your patients what to expect and to contact you if they experience additional symptoms after HPV vaccination.

And finally, if your patient experiences any adverse events after HPV vaccination, you or your patient should report them to VAERS. For more information on the safety data of the HPV vaccine, please see the resources on this page. Thank you.

Web Resources

Summary of HPV Adverse Events:

Questions and Answers about HPV Vaccines (Patient Information)

Dr. Claudia Vellozzi completed her medical degree at Loyola Stritch School of Medicine in Chicago and her MPH at Johns Hopkins in Baltimore. She is board certified in both Family Medicine and Preventive Medicine.

Dr Vellozzi has extensive clinical and public health experience, both domestically and internationally. Her clinical experience includes starting a clinic for underserved Hispanics in Orange County, California, serving as faculty at a Family Medicine Residency Program in Greeley, Colorado, primary clinical care at a rural hospital in Nigeria and she continues to care for patients one-half day weekly at a Grady Neighborhood clinic, in Atlanta. Her areas of work in public health include HIV/AIDS, vaccines and immunization safety, health services research and maternal infant health. She has worked with the Centers for Disease Control and Prevention, World Health Organization and the Commonwealth Fund.

Dr Vellozzi recently returned to the Immunization Safety Office as Deputy Director and has led the H1N1 vaccine safety surveillance activities at the Centers for Disease Control and Prevention.

Dr Vellozzi has published numerous manuscripts in peer reviewed literature.


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