Utilization and delivery: immunizations
Patient group: children and mothers undergoing vaccinations, reports for different age groups Comparison: pure control group (standard practice, status quo, no additional financing) Intervention: any type of P4P Settings: Afghanistan, Argentina, Burundi, Cambodia, Cameroon, Democratic Republic of the Congo, Malawi, Peru, Zambia, Zimbabwe
Outcome	Impact summary	Number of studies	Certainty of the evidence (GRADE)	Comments
Child immunization: % receiving ≥ 1 vaccine	P4P may make little to no difference to outcome: effects inconsistent of small magnitude, ranging from –1 to 1%.	2 (Bonfrer 2014a; Huillery 2017)	Lowa	Indicators assessed across different age groups, 1 in children and 1 in infants. Sensitivity analysis: 1 RCT reported positive effect 1%, moderate‐certainty evidence (1 study only).
Children fully vaccinated (%)	Effects of the intervention are uncertain: literature noted effect sizes ranging from –18% to 38.9%.	8 (Bonfrer 2014b; Chansa 2015; Cruzado de la Vega 2017; de Walque 2017; Friedman 2016a; Friedman 2016b; McMahon 2016;  Zeng 2018)	Lowb	Exact indicators differed across population groups assessed (age groups) and ITS slope and level change captured within range. Sensitivity analysis: 1 RCT estimated at 16.1%, low‐certainty evidence (serious concerns over ≥ 2 risk of bias criteria, 1 study only).
Children receiving BCG (%)	P4P may have small desirable effects: effects ranging from small negative effects (–3.4%) to positive (7%)	8 (Bonfrer 2014a; Bonfrer 2014b; Falisse 2015; Friedman 2016a; Friedman 2016b; Huillery 2017; Zeng 2013, Zeng 2018)	Lowa	Exact indicators differed, summary over indicators in coverage, children aged 12–24 months and different time points. Sensitivity analysis: RCT evidence was 1–7% (2 studies); low‐certainty evidence (critical limitations risk of bias and indirectness).
Children receiving DTP (%)	P4P may have undesirable effects, ranging from –19.7% to +9%	6 (Bonfrer 2014b; Falisse 2015; Friedman 2016a;Friedman 2016b; Matsuoka 2014; Zeng 2018)	Lowc	Exact indicators differed, summary drew on data across coverage and % indicators for children of different age groups receiving DTP 1, 2, 3 and ITS slope and level change captured within range. Sensitivity analysis: RCT effect was 6.1%; low‐certainty evidence (1 study, concerns over risk of bias).
Children receiving measles vaccination (%)	P4P may have desirable effects, ranging from –5% to 18.7%	6 (Binyaruka 2015; Bonfrer 2014b; de Walque 2017; Friedman 2016a; Friedman 2016b; Matsuoka 2014)	Lowc	Indirectness likely as indicators assessed across different populations and ITS slope and level change captured within range. Sensitivity analysis: RCT effect was –3.6%; low‐certainty evidence (1 study, risk of bias concerns).
Children receiving polio vaccination (%)	P4P may have desirable effects, ranging from –7.1% to +23%	7 (Binyaruka 2015; Bonfrer 2014b; de Walque 2017; Falisse 2015; Friedman 2016a; Friedman 2016b; McMahon 2016)	Lowa	Indicators different, ranging from coverage to % receiving specified number of doses. Sensitivity analysis: RCT effect was 21% (low‐certainty evidence; concerns over 1 criterion among risk of bias and 1 study only)
Children receiving pentavalent vaccination (%)	P4P may make little to no difference to the outcome, with effects ranging from –5.7% to 3.1%	3 (Binyaruka 2015; Engineer 2016; McMahon 2016)	Lowa	Sensitivity analysis: RCT effect was –5.7%; moderate‐certainty evidence (downgraded, as 1 study only).
Mothers receiving immunizations (%)	P4P may have desirable effects, ranging from –2.2% to 65.5%	9 (Binyaruka 2015; Bonfrer 2014a; Bonfrer 2014b; de Walque 2017; Falisse 2015; Gertler 2014; McMahon 2016; Zang 2015; Zeng 2018)	Lowd	Indicators were substantively different, ranging from coverage rates, to % of women vaccinated at facilities, to % of women giving birth who had received vaccine. No RCT reported this outcome for this comparison.
Summary	Effects on overarching likelihood of children being vaccinated appeared inconsistent; some vaccinations such as polio, measles and BCG may be positively affected, while others such as DTP may be negatively affected. Low‐certainty evidence.