The literature search yielded 8675 references (Fig. 1). After the screening of titles and abstracts, we selected 150 studies for full-text screening. Seventy-four studies met the inclusion criteria and were included [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86] (Tables 1, 2).

PRISMA flow diagram 2020. Preferred Reporting Items for Systematic Reviews and Meta-Analyses: the PRISMA statement [8]

Details for study type, study quality, place of study, and type of intervention are summarized in Table 3.

The most frequent interventions from the non-outbreak setting were hand hygiene (N = 10) [21,22,23,24,25,26,27,28,29,30], an IPC bundle with several measures included (N = 7) [18, 31,32,33,34,35,36], oral hygiene (N = 6) [38,39,40,41,42,43], antimicrobial stewardship (N = 4) [13,14,15,16] as well as vaccination of residents (N = 3) [44,45,46]. Interestingly, studies from Asia mainly concentrated on oral health (N = 4) [38, 39, 41, 43] and hand hygiene (N = 3) [22, 23, 28], whereas studies from North America drew their attention towards antimicrobial stewardship [13,14,15,16] and hand hygiene [21, 24, 25, 30] (each N = 4). An overview on the results of the included studies in non-outbreak settings is shown in Fig. 2.

Non-outbreak setting, divided in successful and non-successful intervention by type of intervention

The majority of studies in the outbreak setting concentrated on an IPC bundle (N = 24) [47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,