Schaad 2000.

Study characteristics
Methods	An open randomised multicentre study over 4 weeks.
Participants	Children with CF (n = 64) in 5 paediatric centres in Switzerland.
Interventions	A trivalent virosomal influenza vaccine (ASingapore/6/86 (H1N1); A/Shandong/9/93 (H3N2) B/Panama/45/90) (given as either single or 2 doses 4 weeks apart) versus a trivalent subunit influenza vaccine (A/Singapore/6/86 (H1N1); A/Shandomg/9/93 (H3N2); B/Panama/45/90) (given as 1 or 2 doses 4 weeks apart).
Outcomes	1. Adverse effects 2. Antibody level rise
Notes	Antibody levels taken before and 4 weeks after the single or the second immunisation.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as randomised, but no details of method given.
Allocation concealment (selection bias)	Unclear risk	Not discussed.
Blinding (performance bias and detection bias) All outcomes	High risk	Not possible as dose regimens in the treatment groups differ ‐ some participants received a single injection and others received two injections.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	States number of withdrawals, but does not give details of which treatment group they were from or the reason for withdrawal.

CF: cystic fibrosis
IM: intramuscular