Table 3. Inclusion and exclusion criteria.

Inclusion criteria     • Primary research including quantitative studies (e.g., randomized controlled clinical trials, non-randomized controlled trials, cohort studies, case-control studies, cross-sectional analytic studies, incidence or prevalence studies), qualitative studies (e.g., ethnography, phenomenology, grounded theory, and qualitative description), mixed method studies and literature reviews (e.g., systematic, meta-analysis, scoping, narrative, and integrative).     • Published in English     • Sample including or restricted to children under 5 years of age with serious infectious illnesses     • Parents/carers/ first contact health professionals     • Children presenting late or who would have benefitted from earlier treatment     • Research conducted in OECD high income countries. Exclusion criteria     • Published in other languages     • Exclusively about adult illnesses     • Not about children with infectious illness     • Children in the sample all over 5 years of age     • Sample group exclusively children with HIV/ AIDS, complex or chronic childhood illness without infectious illness     • Research conducted in low- or middle-income countries