NEW ORLEANS, LA—A multinational retrospective analysis failed to confirm a possible association between pediatric narcolepsy and the AS03- and MF-59-adjuvanted monovalent pandemic H1N1 vaccines, according to authors of a poster presentation at IDWeek 2016.

However, geographic variation might have complicated efforts to assess such an association, and the study’s statistical power for assessing risk after MF-59 vaccine was “limited,” they cautioned.

“Overall, our results do not support an association between receipt of AS03-adjuvanted 2009 H1N1 vaccine and narcolepsy although our results are based almost exclusively on Arepanrix® use in Ontario,” Steven Black, MD, of the Center for Global Health, Cincinnati Children’s Hospital, in Cincinnati, OH, and coauthors, reported in a poster presentation.

In Europe, an increased risk of narcolepsy was reported among children administered the AS03-adjuvanted 2009 pandemic H1N1 influenza vaccine but that effect might have been influenced by news “media attention bias,” the study authors noted.

The international SOMNIA study was undertaken to evaluate the potential narcolepsy association with the AS03- and MF-59-adjuvanted monovalent pandemic H1N1 vaccines during 2003–2013. Narcolepsy incidence rates were assessed for the periods before, during, and after the pandemic influenza (A)H1N1 vaccination campaigns and a case-control analysis was undertaken to assess relative risks of narcolepsy among children and adults receiving the MF-59 and AS03 vaccines.

“No changes in incidence rates of narcolepsy diagnoses were observed between the period after the start of AS03- or MF-59-containing H1N1 vaccination programs and the period before H1N1 circulation, in any of the age groups or countries except for Sweden, where a steep increase was observed in children 5–19 years in 2010,” the authors noted. “In the primary case control analysis, no association was observed for AS03-containing vaccines in children or adults. Based on three exposed cases, an association with MF-59 vaccine was observed in Argentina in the primary analysis in children, but no association was found when cases from Europe were included.”

The study is funded by the U.S. Centers for Disease Control and Prevention (CDC).