HPV Vaccine Deemed Safe Despite Higher Anaphylaxis Rates

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Main Category: Cervical Cancer / HPV Vaccine
Also Included In: Women's Health / Gynecology
Article Date: 03 Sep 2008 - 0:00 PST

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According to a study published in CMAJ, young women who had human papillomavirus (HPV) vaccination were found to be five to twenty times more likely to have anaphylaxis than women identified in comparable school-based vaccination programs. Researchers, however, also considered the overall rates of anaphylaxis to be low with no serious lasting effects.

Anaphylaxis is a condition associated with vaccinations characterized by sudden onset of adverse events and rapid progression of signs and symptoms in more than one organ. Dr. Julia Brotherton (National Center for Immunization Research and Surveillance of Vaccine Preventable Diseases) and colleagues studied 114,000 women who participated in a 2007 HPV vaccination program in New South Wales, Australia. There were 12 suspected cases of anaphylaxis - eight of which were confirmed - that included symptoms such as difficulty breathing, nausea and rashes. The researchers computed an anaphylaxis incidence rate following HPV vaccination of 2.6 per 100,000 doses administered and compared it to a rate of 0.1 per 100,000 doses of a school-based meningococcal C vaccination program from 2003.

Brotherton and colleagues suggest several reasons for the increased rate of anaphylaxis after HPV vaccinations such as:

• Possible allergic reactions to the components of the vaccine,
• Enhanced adverse event surveillance,
• Higher rates of anaphylaxis in women from mid-adolescence compared with men, and
• Australia's higher anaphylaxis incidence rate.

These Australian findings come at a time when the United Kingdom and other European countries, as well as parts of Canada and the United States, are initiating large-scale HPV vaccination programs. Brotherton and colleagues maintain, however, that although the anaphylaxis rate is significantly higher than comparable vaccination programs, overall rates were very low and the programs should continue.

It is important to have, "Good training for staff administering vaccines in school or other settings in the recognition and management of suspected anaphylaxis and its reporting," concludes Brotherton.

A commentary written by Dr. Neal Halsey (Institute of Vaccine Safety, Johns Hopkins Bloomberg School of Public Health) argues that although anaphylaxis is a rare adverse event, its seriousness warrants vaccine safety studies after vaccine licensing and requires careful management of reactions in immunization clinics. "Before concluding that the HPV vaccine is associated with higher rates of anaphylaxis than other vaccines everywhere, cases in other populations should be reviewed….As of July 21, 2008, 11 cases have been reported [in the US] in 2008. Over 13 million doses of this vaccine have been distributed as of the end of 2007," he concludes.

Drs. Noni MacDonald, Matthew Stanbrook and Paul Hebert write in a CMAJ editorial that this study provides evidence of the safety of the HPV vaccine. The researchers maintain that the study provides an impetus for Canada's public health community, "To restart public discussions about the safety of the HPV vaccine, the precautions taken to mitigate risks if anaphylaxis occurs, and the care taken in surveillance for adverse events following vaccination."

Anaphylaxis following quadrivalent human papillomavirus vaccination
Julia M.L. Brotherton MD MPH, Mike S. Gold MD, Andrew S. Kemp MD PhD, Peter B. McIntyre MD PhD, Margaret A. Burgess MD, Sue Campbell-Lloyd RN, on behalf of the New South Wales Health HPV Adverse Events Panel
CMAJ (2008). 179[6]: pp. 525 - 533.
DOI:10.1503/cmaj.080916
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Written by: Peter M Crosta
Copyright: Medical News Today
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