Study	Reason for exclusion
Abadoglu 2004	Participants were not randomised to active treatment or control (age/sex‐matched controls were selected for the control group)
Ahmed 1997	Non‐randomised before and after study
Ambrosch 1976	Mixed population of patients with rhinitis and asthma with no separate data for asthmatic patients
Andreeva 2007	Not randomised
Ashkenazi 2006	Not on children with asthma
Balluch 1972	No randomisation. No separate asthma data, mixed group of allergic patients
Belshe 2007	Not on children with asthma
Buchanan 2005	Comment on Bueving 2003 study
Busse 2011	Patients with mild and severe asthma randomised to 15 µg or 30 µg H1N1 influenza vaccination, but no placebo arm used in the trial
Campbell 1984	Not clearly stated as being randomised and no response from authors
Chiu 2003	Quasi‐randomised as patients were alternately allocated to treatment groups
De Jongste 1984	Not randomised
Dixon 2006	Cohort study
Kava 1987	Not stated as randomised and no response from authors
Kim 2003	Not stated as randomised
Kramarz 2000	Not randomised
McIntosh 1977	No asthma outcomes measured
Migueres 1987	No randomisation of vaccination in asthmatics (no control intervention)
Modlin 1977	No separate data on asthmatic patients (study of children in 7 chronic disease categories)
Park 1996	No randomisation of vaccination (comparison of influenza vaccination in asthmatics without asthma symptoms or with acute asthma)
Piedra 2005	Non‐randomised study
PRISMA 2005	Case control study (not randomised)
Sakaguchi 1994	No asthma outcomes measured
Sugaya 1994	Self‐selected treatment group (no randomisation)
Tata 2003	Not randomised
Warshauer 1975	No randomisation of asthmatic patients
Watanabe 2005	Not randomised