Previous studies have shown that a small incentive can have a large impact on health behaviors like vaccinating children. New Incentives, an international non-governmental organization (NGO), aims to boost demand for immunization by offering cash incentives to caregivers who have their child vaccinated at a program clinic. In collaboration with New Incentives, IDinsight is conducting a study to see whether this approach will increase immunization in North West Nigeria. This study aims to investigate whether giving cash to caregivers in North West Nigeria who bring their infants to receive vaccination against common infections (tuberculosis, diphtheria, tetanus, pertussis, hepatitis B virus (HBV) infection, Haemophilus influenzae Type B (Hib), pneumococcal bacteria, measles, rotavirus, polio, yellow fever) increases the proportion of children who are immunized. The study's main hypothesis is that New Incentives' program will increase the percentage of children immunized with BCG, any PENTA, or Measles 1 by an average increase of at least 7-percentage points across all program clinics that share a similar profile to the clinics New Incentives will operate in at scale. The study is taking place in Jigawa, Katsina, and Zamfara States between August 2017 and January 2020.

The study will be structured as a two-arm cluster RCT with clinics catchment areas as clusters. One arm will serve as the control (83 clinics) and will operate as the status quo, while the other arm will receive New Incentives' full program (84 clinics). This design will measure the causal effect of New Incentives' program on the likelihood of an infant receiving a vaccine. The unit of treatment and randomization is the clinic catchment, while the unit of measurement for the key outcomes is the individual infant.

Eligible caregivers who bring their infant(s) to a treatment group health facility for immunizations are first enrolled in the program by New Incentives staff, who record caregiver and infant details. If the child has received the vaccination, the caregiver receives the cash incentive, and instructions on when to return for the next vaccination and incentive payment.

Data collection of outcome measures takes place at three points (baseline, midline, and endline) using a series of self-reported surveys of caregivers, examination of the child's health card (where available) and reviewing clinic records. Baseline was completed between August and October 2017, midline is scheduled for March 2019, and endline is planned for November 2019 to January 2020. Across all outcome measurements, sampled infants will be aged between 12 and 16 months (though baseline surveyed some infants aged up to 24 months to increase sample size). These age groups are sampled as they are well beyond the age at which children should receive the program vaccinations. (The Nigerian Routine Immunization schedule aims to give the program vaccinations between birth and 9 months old.) IDinsight does not follow the same infants from baseline to midline to endline but, rather, compares coverage rates in the same age group at each point in time. From the perspective of the participant, taking part in the study involves receiving a researcher into their home, providing informed consent, and answering a 1-hour survey.

Inclusion Criteria:

• Children aged 0 to 16 months can be enrolled in the program and incentives paid to their caregivers
• Children aged 12 to 16 months will have their data measured at endline
• All participants must reside in study clinic catchment areas.
• Vaccination status will be measured by caregiver survey. Caregivers must consent to the survey

Exclusion Criteria:

• Residence outside the study area (self-reported)
• Outside the age range (self-reported)

All participant-level data is anonymized through removing any information that could lead to back-tracking the identity of the respondent - each respondent is allocated a random identification number in place of their name. Anonymized data are currently stored in a password-protected repository on IDinsight's Dropbox site. Access is restricted to IDinsight staff that are on the project.

IDinsight and New Incentives collect various clinic-level data as well for use as covariates and to inform operational decisions. These data are stored in the same repositories and in New Incentives' own password-protected internal dashboard.

Requests for access to data can be made directly to IDinsight (Manager: Zack Devlin-Foltz (zack.devlinfoltz@idinsight.org) and Corresponding Investigator: Dr. Niklas Heusch (niklas.heusch@idinsight.org))

Potential participants in treatment communities likely interact with implementing staff (either to receive the program, or in passing). Potential participants in control communities usually only interact with data collection staff. They are informed about the studies' general goals.