Reference	Objective	Study design	Evidence level
Dexter et al. [562]	To study the effectiveness of different methods to increase vaccine coverage in adults eligible for vaccination	RCT	2C+
Jacobson et al. [563]	To study the effectiveness of different methods to increase vaccine coverage in adults of all age groups	SR	1A+
de Hart et al. [564]	To study the effectiveness of different methods to increase vaccine coverage in elderly persons	PCS	3C+
Jha et al. [565]	To study performance measures, vaccinations and pneumonia rates among high‐risk patients in Veterans Administration health care	RCS	4C+