| Methods |
Retrospective cohort study evaluating the association between the administration of monovalent pandemic inactivated vaccine H1N1 and severe adverse events |
| Participants |
Participants were identified within several administrative and medical databases of the Italian region Emilia Romagna (about 4.4 million individuals). By data linkage participants immunised with Focetria in the 2009 to 2010 season (n = 103,642) were identified. From the unvaccinated population (n = 3,967,917) a matched unexposed cohort was selected using a propensity score. |
| Interventions |
Immunisation with MF59‐adjuvanted, monovalent H1N1 vaccine Focetria (Novartis Vaccines and Diagnostics, Siena, Italy) |
| Outcomes |
Guillain‐Barré syndrome, paralytic syndromes, encephalitis and encephalomyelitis, Bell’s palsy, demyelinating disease, convulsion, autoimmune hepatitis, vasculitis, immune thrombocytopenia |
| Notes |
Government funded |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| PCS/RCS ‐ selection exposed cohort
All outcomes |
Unclear risk |
Unclear description of the vaccinated population |
| PCS/RCS ‐ selection non‐exposed cohort
All outcomes |
Unclear risk |
Using administrative databases |
| PCS/RCS ‐ comparability
All outcomes |
Unclear risk |
Propensity score |
| PCS/RCS ‐ assessment of outcome
All outcomes |
Low risk |
Blind validation process throughout |
| Summary assessment |
Unclear risk |
Unclear |
