HPV shot doesn't trigger autoimmune response

New research indicates that the human papillomavirus vaccine (HPV) Gardasil (Merck & Co.) does not trigger autoimmune conditions such as lupus, rheumatoid arthritis, type 1 diabetes, or multiple sclerosis after vaccination in young women.1 Such news might be reassuring to parents who have withheld the vaccine from their children due to perceived safety concerns surrounding immunization.

To conduct the study, researchers at Kaiser Permanente in Pasadena used electronic health records from 189,629 females ages 9-26 in California who were followed for six months after receiving each dose of the quadrivalent HPV vaccine in 2006-2008. The data indicated no increase in 16 pre-specified autoimmune conditions in the vaccinated population compared to a matched group of unvaccinated girls and women.1

What are the most important strengths of the study? There are two, says lead author Chun Chao, PhD, a research scientist at the Department of Research & Evaluation at Kaiser Permanente Southern California, and adjunct assistant professor in the Department of Epidemiology at University of California, Los Angeles. The first lies in the in-depth chart review by physician experts for diagnosis confirmation and to determine the timing of disease onset, so as to ensure disease onset was after vaccination.

The second strength comes from the statistical approach in comparing the incidence of autoimmune conditions among females vaccinated versus females in the same age range but who were not vaccinated, she says.

"Other strengths include casting a wide net initially to capture all potential new onset autoimmune cases, adequate follow-up time for capturing onset of autoimmune disease, which usually requires some clinical work-up before the diagnosis is made, and a large, diverse, yet well-defined study population," Chao states.

Checking shot safety

Autoimmune reactions have been a longstanding concern surrounding vaccination of all types. Many parents withhold vaccine from their children because of perceived safety concerns.2 However, most associations have stemmed from case reports that have not been confirmed by large, controlled epidemiologic studies.3

The current study looked for autoimmune conditions such as immune thrombocytopenia, autoimmune hemolytic anemia, systemic lupus erythematosus, rheumatoid arthritis, juvenile rheumatoid arthritis, type 1 diabetes, Hashimoto's disease, Graves' disease, multiple sclerosis, acute disseminated encephalomyelitis, other demyelinating diseases of the central nervous system, vaccine-associated demyelination, Guillain-Barré syndrome, neuromyelitis optica, optic neuritis, and uveitis.

To perform the analysis, the researchers identified potential new-onset cases through review of electronic medical records of 149,306 women who had been members of Kaiser Permanente health plans for at least 12 months. Cases identified between January 2004 and the first vaccine were classified as pre-existing and were excluded. The researchers then used the incidence of each condition among vaccinated women and compared it with an estimated incidence for unvaccinated women, which was derived using multiple imputations. Each finding was expressed as an incidence rate ratio (IRR).

Of 719 cases eligible for review, from 31% to 40% of the conditions found were confirmed as new-onset. No IRR was significantly elevated except that for Hashimoto's disease (IRR, 1.29; 95% confidence interval,1.08 - 1.56); however, the investigators concluded there was no consistent evidence for a safety signal for autoimmune thyroid conditions.

Males now included

The recent publication of 2012 immunization schedules by the Advisory Committee on Immunization Practices (ACIP) confirms the panel's 2011 recommendation that males be routinely vaccinated against HPV.4 The ACIP recommended routine vaccination of males ages 11 or 12 with three doses of the quadrivalent HPV vaccine. The recommendation includes that vaccination can begin as young as age 9, and that boys and young men ages 13 to 21 who have not already received the vaccine also should be immunized. The second dose should be administered one to two months after the first dose, and the third dose should be administered six months after the first dose. The American Academy of Pediatrics also has included routine vaccination for males in its 2012 immunization schedule.5

"The elimination of this virus would be beneficial to everyone," says Garry Sigman, MD, adolescent medicine expert at Loyola University Health System in Chicago. "This is a vaccine that has been proven to be effective in eliminating a deadly virus. It should be treated like every other vaccine."

References

  1. Chao, C, Klein NP, Velicer CM, et al. Surveillance of autoimmune conditions following routine use of quadrivalent human papillomavirus vaccine. J Intern Med 2012. 271:193-203.
  2. Gilmour J, Harrison C, Asadi L, Cohen MH, et al. Childhood immunization: when physicians and parents disagree. Pediatrics 2011; 128(Suppl 4):S167-S174.
  3. Chen RT, Pless R, Destefano F. Epidemiology of autoimmune reactions induced by vaccination. J Autoimmunol 2001; 16:309-318.
  4. Advisory Committee on Immunization Practices. Recommended adult immunization schedule: United States, 2012. Ann Intern Med 2012; 156:211-217.
  5. American Academy of Pediatrics. Committee On Infectious Diseases. Policy statement: Recommended childhood and adolescent immunization schedules —United States, 2012. Pediatrics 2012; 129:385-386.