Study	Reason for exclusion
Anjum 2012	Simple pre‐ and post cross‐sectional survey with no controls.
Bar‐Shain 2015	Intervention was a reminder.
Bennett 2015	Age of participants was 18–26 years, not separated to cater for 18–19 years.
Broutet 2013	Review.
Catledge 2014	Pre‐ and postsurvey.
Chan 2015	Pre‐ and poststudy.
Chapman 2010	Pre‐ and postcross‐sectional survey.
Chaves 2000	The study is in Spanish
Chou 2014	Pre‐ and postconsultation surveys.
Chung 2015	Intervention was a reminder.
Dawson 2015	Pre‐ and postintervention study.
Dempsey 2015a	Pre‐ and postintervention study.
Dempsey 2015b	Pre‐ and poststudy.
Donahue 2016	Intervention was a reminder.
Dorji 2015	Descriptive study, with no intervention and control arms.
Farmar 2016	Pre‐ and postintervention study.
Fujiwara 2013	Questionnaire survey, with no intervention and control.
Furlan 2010	Descriptive study with no intervention.
Gargano 2014	Descriptive study with no intervention.
Gillespie 2011	Questionnaire survey in an ineligible age group.
Gordon 2013	Descriptive study, with no intervention.
Gottvall 2010	Quasi‐experimental intervention study.
Hadley 2014	Descriptive study.
Hofman 2013	Pre‐ and post‐test evaluation.
Hull 2016	Pilot cross‐over study.
Iqbal 2016	Age group is 11–25 years and data not stratified by age group.
Kim 2015	Pre‐ and post‐test study.
Kwan 2011	Pre‐ and postevaluation study.
Kwang 2016	Pre‐ and poststudy in an ineligible age group.
Lai 2013	Quasi‐experimental time series.
LaMontagne 2011	Cross‐sectional study.
Marek 2012	Simple pre–post survey.
Meneses Echavez 2015	Pre‐ and postintervention with no control.
Moss 2012	Pre‐ and postintervention survey.
Ortiz 2016	Pilot cross‐sectional study.
Perkins 2016	Cross‐sectional survey.
Pierre‐Victor 2017	Pre‐ and poststudy.
Reiter 2011	Pre‐ and postevaluation study.
Ruffin 2015	Intervention was a reminder.
Sales 2011	Pre‐ and poststudy.
Soldan 2006	Review.
Spleen 2012	Pretest/post‐test assessment.
Stokley 2015	Review.
Szilagyi 2011	Intervention was a reminder.
Tiro 2016	Pre‐ and postsurvey.
Unti 1997	Pre‐ and postsurvey.
Won 2015	Outcomes were trust and participation in school‐located immunisation programmes, and none of our outcomes of interest was reported.
Zhou 2003	Pre‐ and postintervention survey.