HPV Vaccine Side Effects: Updated Gardasil Safety Analysis

The cervical cancer vaccine, Gardasil, was appoved by the FDA in June 2006. Human Papillomavirus (HPV) has been shown to be responsible for many cases of cervical cancer. Gardasil prevents the development of cervical cancer by preventing HPV infection. This HPV vaccine was approved for use in females ages 9 to 26 years, and it is currently recommended that girls ages 11 to 12 years are vaccinated. Now that over 23 million doses of the vaccine have been distributed, it is easier to discern the common side effects and life-threatening conditions that may result after HPV vaccination.

Common Gardasil Side Effects

A recent analysis of HPV vaccine side effects was published in the Journal of the American Medical Association (JAMA). Researchers analyzed 12,424 reports of side effects following HPV vaccination. The most frequently reported side effects include the following:

Partial or complete loss of consciousness

Dizziness

Nausea

Headache

Injection site reactions

Approximately 94% of the reported side effects were not considered to be serious.

HPV Vaccine Safety: Serious Side Effects

Approximately 6% of reported side effects were serious and included 32 reports of death. Medically important serious events included the following:

Death

Anaphylactic reaction

Deep vein thrombosis

Guillain-Barre Syndrome

Hypersensitivity

Transverse myelitis (inflammation across the width of the spinal cord)

Inflammation of the pancreas

Blood clot in the lung

Convulsion

Hives

Autoimmune disorder

While these reported side effects are very serious, they did not occur very frequently. For example, for every 100,000 vaccines distributed, death occured 0.1% of the time. Additionally, there is no evidence that directly links the HPV vaccine to each of the serious side effects reported. Therefore, the reported events may have only coincidentally followed vaccination.

Most of these HPV vaccine side effects were encountered in clinical testing of the vaccine, prior to licensing. However, fainting and deep vein thrombosis are two side effects that were not common during early clinical studies of the cervical cancer vaccine, and according to the report in JAMA, now appear to occur at higher-than-expected rates. However, most patients that experienced a blood clot had a known risk factor. In addition, Kenneth Alexander, MD, PhD, of the University of Chicago speculates that incidences of fainting in these young girls may be caused by fear of the needle, and not necessarily the vaccine itself.

This recent report that details the incidence of HPV vaccine side effects in a larger population of people enables women to more accurately weigh the risk of experiencing side effects from HPV vaccination against the risk of developing cervical cancer in the future.