Comment on the contribution by Souayah et al., “Guillain–Barré syndrome after Gardasil vaccination: Data from Vaccine Adverse Event Reporting System 2006–2009”

Since reporting is voluntary, VAERS data are subject to reporting biases, such as under-reporting and stimulated reporting (e.g., after the introduction of a new vaccine or when there is publicity around a vaccine). [...]the authors note that VAERS reports of GBS following HPV4 had a peak onset during the first two weeks following vaccination, which only partially overlaps the period of time of increased GBS risk found following the "swine flu" vaccine in 1976 [11].