This article presents four cases in which teen-aged girls developed symptoms of neuromyelitis optica (NMO) within four to five months after inoculation with the quadrivalent human papillomavirus (qHPV) vaccine Gardasil. The authors regard these cases as "noteworthy."
They say that NMO may have been triggered by these vaccinations, although the data currently available cannot establish a pathogenic link. However, they conclude that for now, the prevention of cervical cancers outweighs the low adverse event profile of the qHPV-vac, and postmarketing pharmacosurveillance remains crucial to assess the vaccine's long-term safety.
The authors searched for NMO cases entered in the Vaccine Adverse Events Reporting System (VAERS) database between 2006 and 2009.
The intervals between qHPV-vac vaccination and symptom onset were consistently longer than in the five published cases in which multiple sclerosis occured an average of 9.2 days following administration of this vaccine.
They note that NMO is rare (0.25-1/100,000) and may be even rarer in adolescents, given a median age at onset of 39 years. With approximately 9 million subjects vaccinated with qHPV-vac in the United States and Europe as of September 2009, they say the reported NMO cases are unexpected and may not simply reflect the natural disease prevalence.
Other rare but far more prevalent antibody-mediated autoimmune diseases are not reported with similar frequency. They identified two cases of scleroderma (prevalence 5-25/100,000), five cases of Wegener granulomatosis (prevalence 2.4-15.6/100,000), and nine cases of myasthenia gravis (prevalence 4-10/100,000).
They retrieved only eight NMO cases from the entire VAERS database. In addition to the four cases they present, two were reported in association with hepatitis B virus vaccinations (in patients age 47 and unknown), and one case each occurred after influenza and DTP (diphtheria, pertussis and tetanus) vaccinations (age 53 and 18). They say this suggests that the HPV vaccination might be overrepresented given that qHPV-vac was approved only recently and has been given substantially less frequently than the other vaccines.