Gargano 2015.

Methods	Randomised trial in the USA between November 2011 and July 2013
Participants	Participants: parents of middle‐ and high‐school students Number enrolled: 6 middle‐ and 5 high‐schools Study population: parents of middle‐ and high‐school students enrolled in schools that were participating in a study focused on evaluating approaches to promoting adolescent vaccination.
Interventions	Intervention: 1. parent‐only adolescent vaccination education and 2. parent and adolescent education Description: 3‐ to 5‐month health education for parents only or parents and adolescents. The intervention consisted of a brochure for parents and a 2‐ to 3‐day curriculum for adolescents. The parent education package included an invitation letter and a gift card valued at USD 20. Duration: 2 years Comparison: usual practice Description of the comparison: none. Vaccine target: Tdap, meningococcal, HPV, and influenza vaccines Disease targeted: not specified Number of doses: not stated
Outcomes	Parent willingness to have their adolescent vaccinated in a school‐located vaccination clinic Attitudes and beliefs towards vaccination
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No description.
Allocation concealment (selection bias)	Unclear risk	No description.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	The outcome is an objective measure.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	The outcome is an objective measure.
Incomplete outcome data (attrition bias) All outcomes	High risk	Low response rate.
Selective reporting (reporting bias)	Unclear risk	No description.
Other bias	Low risk	No evidence of other biases.