Reports of side effects following vaccination with Merck's Gardasil, a drug to prevent human papillomavirus (HPV) and genital warts, have been collected voluntarily through the Vaccine Adverse Event Reporting System (VAERS). Researchers with the Centers for Disease Control and Prevention reviewed the side effects filed through VAERS between 2006 and 2008, a time when 24 million Gardasil doses were given to American girls and young women. The analysis was published in 2009 with the warning that voluntary data often could not be verified.
Since 2006, more than 40 million doses of Gardasil have been administered in the United States, with 20,096 reports of adverse events following vaccination sent through VAERS. The Centers for Disease Control and Prevention’s Vaccine Safety Datalink Project report that no significant negative outcomes have been proven.
One of the most common neurological side effects reported following the vaccine was blood clots or venous thromboembolism, including four deaths from blockage in the main artery to the lung. According to the National Heart Lung & Blood Institute, a thrombosis is a blood clot that develops within a vein. Blood clots can be damaging when they stop the flow of blood or when they break away and block blood flow to an important organ.
Along with blood clots, vasovagal syncope, or fainting, was one of the most commonly reported effects following the vaccine, according to the CDC report. According to the Mayo Clinic, syncope is a sudden drop in blood pressure and heart rate which slows blood flow to the brain and causes a brief loss of consciousness. Fainting is not normally considered serious but among the 1,896 reports of syncope, hundreds resulted in unexpected falls and head injuries and lacerations to other parts of the body.
There were 42 cases of Guillain-Barré Syndrome reported but only 12 cases were confirmed as GBS at the time the analysis was published. In GBS, the body's immune system attacks part of the peripheral nervous system, according to the National Institutes of neurological Disorders and Stroke. Recovery from GBS may occur in as little as a few weeks to several years. Relapses and residual effects from the disease are not uncommon.
About 150 of the 937 reports of headaches after HPV vaccination were serious enough to require hospitalization.
There were 51 reports of autoimmune disorders including connective tissue disorders, lupus, rheumatoid arthritis, and Sjögren syndrome, a disease which causes dry eyes and mouth. An autoimmune disorder occurs when a body's immune system attacks itself, according to the U.S. National Library of Medicine.
There were 693 hypersensitivity reports considered valid by the CDC reviewers. Hypersensitivity reactions included hives, rash, joint pain, shock due to low blood pressure, bronchial spasm, and eye swelling.
Inflammation of the Spinal Cord
Inflammation of the spinal cord, or transverse myelitis, was reported in 10 cases. Inflammation attacks can damage or destroy myelin, the protective insulation surrounding nerve cell fibers. This damage can cause scarring in the nervous system that interrupts communication between the spinal cord nerves and the rest of the body, according to the National Institutes of Neurological Disorders and Stroke. Diseases like multiple sclerosis and GBS are caused by damage to the myelin sheath.
Motor Neuron Disease
Three young women reportedly died after developing a fast progressing motor neuron disorder a few months after receiving the vaccine. One of the deaths was confirmed by autopsy as amyotropic lateral sclerosis, or ALS. According to the National Institute of Neurological Disorders & Stroke, ALS causes degeneration of the nerve cells in the central nervous system that controls muscle movement. One cause of death was pending and one could not be confirmed, according to the CDC analysis.
Among the nine cases of pancreatitis, or inflammation of the pancreas, reported, all of young women had pre-existing risk factors for the vaccine. The risk factors were gallstones, alcohol use, increased triglycerides or high levels of fat in the blood, viral infection, estrogen use and mild obesity. The implication is that physicians should screen people for these and other risk factors to determine if they are healthy enough to be vaccinated.
JAMA: Postlicensure Safety Surveillance for Quadrivalent Human Papillomavirus Recombinant Vaccine http://jama.ama-assn.org/cgi/content/full/302/7/750
MayoClinic.com: Vasovagal syncopehttp://www.mayoclinic.com/health/vasovagal-syncope/ds00806
Medline Plus: Auoimmune Diseases http://www.nlm.nih.gov/medlineplus/autoimmunediseases.html
National Heart Lung & Blood Institute http://www.nhlbi.nih.gov/health/dci/Diseases/Dvt/DVT_WhatIs.html
New England Journal of Medicine: Human Papillomavirus Vaccination — Reasons for Caution http://content.nejm.org/cgi/content/full/359/8/861