Background: Text message (short message service, SMS) reminders and incentives are two demand-side interventions that have been shown to improve health care–seeking behaviors by targeting participant characteristics such as forgetfulness, lack of knowledge, and transport costs. Applying these interventions to routine pediatric immunizations may improve vaccination coverage and timeliness.
Objective: The Mobile Solutions for Immunization (M-SIMU) trial aims to determine if text message reminders, either with or without mobile phone–based incentives, sent to infant’s parents can improve immunization coverage and timeliness of routine pediatric vaccines in rural western Kenya.
Methods: This is a four-arm, cluster, randomized controlled trial. Villages are randomized to one of four study arms prior to enrollment of participants. The study arms are: (1) no intervention (a general health-related text message will be texted to this group at the time of enrollment), (2) text message reminders only, (3) text message reminders and a 75 Kenyan Shilling (KES) incentive, or (4) text message reminders and a KES200 incentive. Participants assigned to study arms 2-4 will receive two text message reminders; sent 3 days before and one day before the scheduled immunization visit at 6, 10, and 14 weeks for polio and pentavalent (containing diphtheria, tetanus, pertussis, hepatitis B, and Haemophilus influenza type b antigens) type b antigens) vaccines, and at 9 months for measles vaccine. Participants in incentive arms will, in addition to text message reminders as above, receive mobile phone–based incentives after each timely vaccination, where timely is defined as vaccination within 2 weeks of the scheduled date for each of the four routine expanded program immunization (EPI) vaccination visits. Mother-infant pairs will be followed to 12 months of age where the primary outcome, a fully immunized child, will be ascertained. A fully immunized child is defined as a child receiving vaccines for bacille Calmette-Guerin, three doses of pentavalent and polio, and measles by 12 months of age. General estimating equation (GEE) models that account for clustering will be employed for primary outcome analyses.
Results: Enrollment was completed in October 2014. Twelve month follow-up visits to ascertain immunization status from the maternal and child health booklet were completed in February 2016.
Conclusions: This is one of the first studies to examine the effect of text message reminders on immunization coverage and timeliness in a lower income country and is the first study to assess the effect of mobile money-based incentives to improve immunization coverage.
Trial Registration: Clinicaltrials.gov NCT01878435; https://clinicaltrials.gov/ct2/show/NCT01878435 (Archived by WebCite at http://www.webcitation.org/6hQlwGYJR)
The decade from 2010 to 2019 has been dubbed the “Decade of Vaccines” with renewed focus on immunization by major international groups like World Health Organization, United Nations Children's Emergency Fund, the Global Alliance for Vaccines, and the Bill and Melinda Gates Foundation [- ]. A key component in the Global Vaccine Action Plan is the recognition that both demand- and supply-side deficiencies need to be addressed in order to achieve universal immunization [ ]. Ensuring more infants receive timely vaccination is a major component in efforts to reduce child mortality by two-thirds and achieve Millennium Development Goal 4 [ ]. Every year, immunization programs are estimated to save over 2.5 million lives globally [ ], with the majority of deaths averted occurring in Africa [ ].
Timely vaccination is important for several reasons. First, the diseases that pediatric vaccines protect against often have highest morbidities and mortalities at earlier stages of life. Delays of infant immunization have been associated with increased cases of pertussis [, ], hepatitis B [ ], and Haemophilus influenza type b [ ]. Second, timely vaccination heightens population herd immunity levels [ ], thereby protecting those that are too young to be vaccinated or are medically contraindicated. Delays in vaccination lessen population coverage and create a pool of susceptible individuals, thereby increasing the pathogen’s ability to spread and theoretically increasing the risk of exposure.
Interventions to improve immunization coverage and timeliness are important because approximately 1 in 13 children in Kenya and 1 in 5 children in our study site, Siaya County in western Kenya, will die before their 5th birthday, with the majority of deaths attributed to infectious diseases [, ]. Many of these deaths are preventable by vaccination, yet many children in Kenya are not vaccinated or are vaccinated late [ , ].
Two demand-side interventions, text message (short message service, SMS) reminders [- ] and small monetary incentives [ - ], have been shown to motivate positive health behaviors in resource constrained settings. Moreover, text message reminders have been shown to modestly improve immunization coverage in the United States [ - ]; however, the efficacy of text message reminders to improve immunization coverage in sub-Saharan Africa, until recently [ , ], has neither been evaluated nor used in conjunction with monetary incentives. This randomized controlled trial will test whether text messaging reminders, either with or without mobile phone-based incentives, can improve timeliness and coverage of routine pediatric immunizations.
Critically, the success of our pilot study in a neighboring division, Karemo, shows that a mobile phone-based system that delivers incentives and text messaging reminders is technically feasible and welcomed by the community . Lessons and challenges learned from the pilot study will be incorporated into the design of the current cluster randomized controlled trial.
The Mobile Solutions for Immunizations (M-SIMU) study is a four-arm, cluster, randomized controlled trial, which evaluates the impact of providing caregivers text message reminders and monetary incentives on the proportion of children that are fully vaccinated by 12 months of age.
The M-SIMU study is a four-arm, cluster, randomized controlled trial to evaluate the impact of text message reminders and monetary incentives on pediatric immunization coverage and timeliness in rural western Kenya. Villages, as defined by the Kenyan Medical Research Institute and (KEMRI) and Centers for Disease Control and Prevention (CDC) Health and Demographic Surveillance System (HDSS), are the units of randomization. Villages will be randomized to one of four study arms in a 1:1:1:1 allocation ratio (). The study arms include: (1) control, (2) text message reminders, (3) text message reminders plus a 75 Kenyan Shillings incentive (KES; KES85 = US$1 as of August 2015) and, (4) text message reminders plus a KES200 incentive. Text message reminders are sent three days and one day before pentavalent vaccination visits scheduled at 6, 10, and 14 weeks, and measles vaccination at 9 months of age. Incentives are delivered to the participant’s mobile phone if the participant’s child is brought for immunization within 2 weeks of the scheduled date. All eligible mothers/caretakers residing within a study village will be assigned to the study arm that the village was allocated.
Setting and Participants
The M-SIMU study is located in Rarieda and Gem Districts of Siaya County, Kenya. Malaria, tuberculosis, and human immunodeficiency virus transmission are highly prevalent in this rural setting . In 2008, the under-5 mortality rate was 212 deaths per 1000 live births, with pneumonia and diarrhea as common causes of childhood mortality [ ].
The study site is nested within boundaries defined by KEMRI/CDC HDSS. Since 2001, the HDSS systematically collects information on births, deaths, migration, morbidity, and demographics every 4 months for a population of over 220,000 people. Within the HDSS, several disease specific studies have been conducted, including randomized controlled trials for bed-net efficacy, and rotavirus vaccine efficacy [, ].
Prior to enrollment of the randomized controlled trial, a baseline survey was conducted in the study villages to obtain recent estimates of vaccination coverage for sample size calculation and to collect sociodemographic variables, such as mobile phone ownership and distance to nearest health facility, to perform a restricted randomization of study villages . Additionally, three focus group discussions with 10 to 15 mothers who have a child 12- to 23-months-old were conducted to solicit local and contextual-specific feedback on the content and timing of the text message reminders, incentive amounts, willingness to receive reminders and incentives, and to anticipate any problems or complications associated with delivering text message reminders and incentives.
Villages are included in the cluster randomized controlled trial if they are located within either Gem or Asembo HDSS boundaries. Villages are excluded from the M-SIMU study if there are active immunization intervention/programs (e.g., nongovernmental organizations conducting immunization-related activities, outreach immunization clinics, etc.) that might confound study outcomes. Sample size calculations were conducted to determine the number of villages needed to be able to detect a 15% absolute difference in full immunization coverage at 12 months of age between control and intervention arms.
To ensure accurate population numbers, KEMRI/CDC HDSS casually employs ‘village reporters’ to identify births, deaths, and pregnancies within their community. For the M-SIMU trial, village reporters will be provided a simple mobile phone and trained to send a birth or death notification text message to the RapidSMS server, a free and open-source platform. The notification text message will include the study village and compound number. The RapidSMS server then automatically relays the notification to a field-based Community Interviewer (CI). Following receipt of a birth notification, the CI will visit the newborn’s compound to explain the trial and screen the mother/caretaker for the following eligibility criteria described in.
Criteria for participant enrollment into the Mobile Solutions for Immunization (M-SIMU) trial.
- Mother of infant aged 0- to 4-weeks during the study period
- Current resident of one of the study villages
- Willing to sign informed consent for the study
- Plans to move out of the study area in the next 6 months
- Has already received immunizations other than birth dose of bacille Calmette-Guerin or polio
- Will not bring infant to an M-SIMU identified clinic ( )
Mothers are eligible independent of mobile phone ownership. Mothers only need to have access to a mobile phone, whereby access is defined by the mother and could include someone that lives in household, compound, or a neighbor. If no mobile phone can be identified, the mother may use the CI’s phone.
Eligible mothers will be required to provide both oral and written informed consent to the CI. Upon providing consent, the CI will send an enrollment text message to the RapidSMS server containing the mother’s village and compound number, the phone number that can be used to receive text message reminders, the child’s date of birth, the preferred language to receive text message reminders (English, Kiswahili, or Dholuo), and the baby’s first and last name. Upon completion of a successful enrollment text message, the RapidSMS server sends a personalized text message to the mother welcoming her to the study (see).
The interventions, text message reminders and incentives, are designed to motivate mothers and increase demand for routine pediatric immunizations.
Text message reminders are a component of all three intervention arms and will be sent to the mobile phone number participants identified at enrollment. Text message reminders will be sent using RapidSMS on both 3 and 1 days before the scheduled immunization visits at 6, 10, and 14 weeks for the three doses of pentavalent vaccine and at 9 months for measles as per Kenyan Expanded Programme on Immunization (KEPI) guidelines. Text message reminders will be sent as in English, Kiswahili, or Dholuo language according to the mother’s preference as indicated at enrollment. If a pentavalent vaccination is given later than the scheduled date, then text message reminders for the subsequent pentavalent dose will be reprogrammed to occur at 4 weeks from the date of vaccine receipt, as per KEPI guidelines. As an example, if a child receives pentavalent1 at 8 weeks of age (scheduled to be given at 6 weeks), the immunization reminders for pentavalent2 will be sent when the child is 12-weeks old (instead of the KEPI schedule of 10 weeks).
Text message reminders are composed of a core text and a motivational saying (See). The core message states which vaccine is due, and if the participant is in an incentive arm, reminds the mother how much money she will receive if the child is vaccinated in a timely manner. The motivational sayings attached at the end of the text message were chosen from the results of focus group discussions held with caregivers of children aged 12- to 23-months old. The four sayings are “Vaccines save Kenyan babies lives,” “Baby < INSERT BABY FIRST NAME> is happy when healthy “Most <INSERT DISTRICT: ASEMBO or GEM> babies get vaccinated, be one of them,” and “Vaccines are available now.” For each vaccine dose, one of the four motivational sayings is randomly selected, with replacement, by the RapidSMS software. The same motivational saying is used for the 3- and 1-days reminder for that particular vaccine dose.
Mobile phone–based monetary incentives are a component of study arms numbers three and four. In both arms, the conditions and delivery of the incentive are identical; only the incentive amount differs. In addition to receiving text message reminders, mothers will receive either KES75 (arm #3;) or KES200 (arm #4) on their mobile phone for each timely dose of pentavalent and measles vaccine, defined as vaccination within 2 weeks of the scheduled date (i.e., pentavalent1 at 6 weeks, pentavalent2 four weeks after pentavalent1 received, pentavalent3 four weeks after pentavalent2 received, and measles at 9 months). If a mother brings her child for vaccination any time 2 weeks after the scheduled date, no incentive will be transferred. Mobile-money incentives will be transferred using the preferred mobile money network of the participant and are aimed to be delivered within 24 hours of a timely vaccination.
|Message Type||Message Timing||Arm 1: Control||Arm 2 : Reminders Only||Arm 3: Reminders + KES75 Incentive||Arm 4: Reminders + 200KES Incentive|
|Enrollment message||Enrollment||Thank you for enrolling Baby ||Thank you for enrolling your child in the KEMRI/CDC M-SIMU study. You will get periodic reminders for Baby BABY’S FIRST NAME‘s vaccinations. The greatest wealth is health.||Thank you for enrolling your child in the KEMRI/CDC M-SIMU study. You will get periodic reminders for Baby BABY’S FIRST NAME’s vaccinations. The greatest wealth is health.||Thank you for enrolling your child in the KEMRI/CDC M-SIMU study. You will get periodic reminders for Baby BABY’S FIRST NAME‘s vaccinations. The greatest wealth is health.|
|3-day reminder message||3 days before EPI due date||No message||Tell Mama ||Tell Mama BABY’S FIRST NAME that VACCINE NAME vaccine is due this week. You get KES75 if Baby vaccinated in next 2 weeks. MOTIVATIONAL MESSAGE||Tell Mama BABY’S FIRST NAME that VACCINE NAME vaccine is due this week. You get KES200 if Baby vaccinated in next 2 weeks. MOTIVATIONAL MESSAGE|
|1-day reminder message||1 day before the EPI due date||No message||Tell Mama BABY’s FIRST NAME that VACCINE NAME vaccine is due this week. Go to the clinic if you haven’t already. MOTIVATIONAL MESSAGE||Tell Mama BABY’S FIRST NAME that VACCINE NAME vaccine is due this week. Go to the clinic if you haven’t already. MOTIVATIONAL MESSAGE||Tell Mama BABY’S FIRST NAME thatVACCINE NAME vaccine is due this week. Go to the clinic if you haven’t already. MOTIVATIONAL MESSAGE|
|Motivational message||1 of 4 motivational messages randomly selected and appended to the end of the 3- and 1-day reminders; Motivational message is the same for the 1st and 3rd day reminder of the specific vaccine dose||No message||1. Vaccines save Kenyan babies lives; 2. |
We thank the Gem and Asembo communities, KEMRI/CDC-Kisumu and project staff. The authors also thank Maurice Ombok for preparing the randomization map. The M-SIMU study is dedicated to the late Dan Odipo Orao; a motivated student, a loving husband, a caring father, a hard-working colleague, and a dear friend. Funding was obtained through the Bill Melinda Gates Foundation (BMGF) and awarded to the International Vaccine Access Center (IVAC) at the Johns Hopkins University Bloomberg School of Public Health.
Conflicts of Interest
Multimedia Appendix 1
Peer review summary report from scientific steering committee.PDF File (Adobe PDF File), 57KB
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|CDC: Centers for Disease Control and Prevention|
|CI: community interviewer|
|ERC: ethical review committee|
|FIC: fully immunized child|
|GEE: general estimating equation|
|HDSS: health and demographic surveillance system|
|HFR: health facility recorder|
|KEPI: Kenyan Expanded Programme on Immunization|
|KES: Kenyan Shilling|
|M-SIMU: Mobile Solutions for Immunization|
|MCH: maternal and child health|
|SSC: scientific steering committee|
Edited by G Eysenbach; submitted 25.10.15; peer-reviewed by S Muhula, J Kaewkungwal; comments to author 20.01.16; revised version received 22.01.16; accepted 22.01.16; published 17.05.16Copyright
©Dustin G Gibson, E. Wangeci Kagucia, Benard Ochieng, Nisha Hariharan, David Obor, Lawrence H. Moulton, Peter J. Winch, Orin S Levine, Frank Odhiambo, Katherine L. O'Brien, Daniel R. Feikin. Originally published in JMIR Research Protocols (http://www.researchprotocols.org), 17.05.2016.
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