Main outcome measures in the study were: Incidence of acute infectious and post-infectious polyneuritis (Guillain-Barré syndrome), acute transverse myelitis, optic polyneuritis, facial nerve palsy, anaphylactic shock, seizure, multiple sclerosis, autoimmune thrombocytopenia, type 1 diabetes mellitus, juvenile and rheumatoid arthritis, narcolepsy, and death of unknown cause stratified by sex, age, and season1. But what is the guarantee that these outcomes are owing to vaccination. These might be just possible that these occur in the general population. Or else two cohorts should be selected: one vaccinated and other unvaccinated and the rates should be compared as the coverage of vaccine is not 100% (82% to 93%).

Reference:

1. BMJ 2012;345:e5823

Competing interests: None declared