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Sleep Med Rev. 2018 Apr;38:177-186. doi: 10.1016/j.smrv.2017.06.006. Epub 2017 Jun 20.

Incidence of narcolepsy after H1N1 influenza and vaccinations: Systematic review and meta-analysis.

Author information

1
Central Finland Central Hospital, Department of Neurology, Jyväskylä, Finland; University of Helsinki, Department of Neurological Sciences, Helsinki, Finland. Electronic address: tomi.sarkanen@ksshp.fi.
2
University of Helsinki, Department of Neurological Sciences, Helsinki, Finland; HUS Medical Imaging Center, Helsinki University Central Hospital, Department of Clinical Neurophysiology, Finland.
3
Gui-de-Chauliac Hospital, CHU Montpellier, Inserm, U1061, France; National Reference Centre for Orphan Diseases, Narcolepsy, Idiopathic hypersomnia and Kleine-Levin Syndrome, Sleep Disorders Center, France.
4
University of Helsinki, Department of Neurological Sciences, Helsinki, Finland; Helsinki Sleep Clinic, Vitalmed Research Centre, Finland.

Abstract

An increased incidence of narcolepsy was seen in many countries after the pandemic H1N1 influenza vaccination campaign in 2009-2010. The H1N1 vaccine - narcolepsy connection is based on observational studies that are prone to various biases, e.g., confounding by H1N1 infection, and ascertainment, recall and selection biases. A direct pathogenic link has, however, remained elusive. We conducted a systematic review and meta-analysis to analyze the magnitude of H1N1 vaccination related risk and to examine if there was any association with H1N1 infection itself. We searched all articles from PubMed, Web of Science and Scopus, and other relevant sources reporting the incidence and risk of post-vaccine narcolepsy. In our paper, we show that the risk appears to be limited to only one vaccine (Pandemrix®). During the first year after vaccination, the relative risk of narcolepsy was increased 5 to 14-fold in children and adolescents and 2 to 7-fold in adults. The vaccine attributable risk in children and adolescents was around 1 per 18,400 vaccine doses. Studies from Finland and Sweden also appear to demonstrate an extended risk of narcolepsy into the second year following vaccination, but such conclusions should be interpreted with a word of caution due to possible biases. Benefits of immunization outweigh the risk of vaccination-associated narcolepsy, which remains a rare disease.

KEYWORDS:

Autoimmune diseases; Cataplexy; H1N1; Influenza; Narcolepsy; Pandemrix; Vaccination

PMID:
28847694
DOI:
10.1016/j.smrv.2017.06.006
[Indexed for MEDLINE]

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