Child immunization is not a one-time behavior; rather, it is a repeated behavior within a specific timeframe. Not only the low immunization, but also the dropout of immunization and the delayed immunization from the recommended immunization schedule are prevalent and high in Africa. The most common reason for the incomplete vaccination is that caregivers thought the children had already been fully immunized (44.8%), according to Nigeria Multiple Indicator Cluster Survey (MICS) conducted in 2016/2017.

Caregivers' misconception of the complete immunization can be attributed to the complicated immunization schedule. In Nigeria, infants are supposed to receive 9 different types of vaccines at 5 different times within the first year since the births. To make things more complicated, the vaccine schedule changes over time; for example in Nigeria, the new vaccine, inactivated polio vaccine (IPV) was introduced in 2015 to be received at 14 weeks after births, and rotavirus vaccine and meningococcal A vaccine are scheduled for the introduction in 2019.

In this complicated and rapidly-changing environment regarding vaccination schedule, the goal of the study is to improve the understanding of vaccination completion and children's vaccination status among caregivers, which can then lead to the improved rate of full vaccination among children.

Objectives The main objectives of this study are to understand the impact of providing the general and tailored information on the vaccination schedule and vaccination status of women's children on the vaccine take-up. In this study, the investigators focus on women who has a child who is 12 months old or younger.

Hypothesis

The main hypothesis of this proposed study are as follows:

1. Information on vaccination among caregivers: the general and tailored information on vaccination schedule and child's vaccination status, improves the knowledge on benefit and understanding of vaccination completion, vaccination schedule and the vaccination status of the children among caregivers
2. Full immunization rate: through the improved knowledge level on the concept of vaccination completion and their children's vaccination status, the proposed study increases the full immunization rate among children

Background and Objectives Despite the proven benefit of vaccines, the child immunization rate has been stagnant and the rate in African countries lags behind other regions in the world. For example, the global coverage of three doses diphtheria-tetanus-pertussis (DPT3) has been stagnant at 85% since 2015, while DPT3 coverage in Africa remains at 72% since 2010. The distribution of unvaccinated children is unequal; out of about 20 million infants who are not fully vaccinated, more than 20 percent of them reside in three countries, including Nigeria, the proposed study site. Furthermore, Nigeria is one of the few countries where the coverage of DPT3 coverage has decreased over time: 54 percent in 2010 to 42 percent in 2017.

Child immunization is not a one-time behavior; rather, it is a repeated behavior within a specific timeframe. Not only the low immunization, but also the dropout of immunization and the delayed immunization from the recommended immunization schedule are prevalent and high in Africa. The most common reason for the incomplete vaccination is that caregivers thought the children had already been fully immunized (44.8%), according to Nigeria Multiple Indicator Cluster Survey (MICS) conducted in 2016/2017.

Caregivers' misconception of the complete immunization can be attributed to the complicated immunization schedule. Each type and dose of vaccine has its own significance in terms of the type of preventable disease and the achievable efficacy level. In Nigeria, infants are supposed to receive 9 different types of vaccines at 5 different times within the first year since the births. For example, oral poliovirus vaccine (OPV) is to protect infants from contracting polio, a highly contagious disease. At present, Nigeria is one of the three countries in the world, which have not eliminated polio. Infants are scheduled to receive OPV four times; at birth, 6, 10, and 14 weeks. The efficacy of the first dose OPV (oral polio vaccine) is 82%, while the second and the third doses are 90% and 99% or more, respectively. To make things more complicated, the vaccine schedule changes over time; for example in Nigeria, the new vaccine, inactivated polio vaccine (IPV) was introduced in 2015 to be received at 14 weeks after births, and rotavirus vaccine and meningococcal A vaccine are scheduled for the introduction in 2019.

In this complicated and rapidly-changing environment regarding vaccination schedule, the goal of the study is to improve the understanding of vaccination completion and children's vaccination status among caregivers, which can then lead to the improved rate of full vaccination among children.

Objectives The main objectives of this study are to understand the impact of providing the general and tailored information on the vaccination schedule and vaccination status of women's children on the vaccine take-up. This study focuses on women who has a child who is 12 months old or younger.

Hypothesis

The main hypothesis of this proposed study are as follows:

1. Information on vaccination among caregivers: the general and tailored information on vaccination schedule and child's vaccination status, improves the knowledge on benefit and understanding of vaccination completion, vaccination schedule and the vaccination status of the children among caregivers
2. Full immunization rate: through the improved knowledge level on the concept of vaccination completion and their children's vaccination status, the proposed study increases the full immunization rate among children

Literature Review Knowledge is powerful in shaping people's health behaviors. In a situation where the health behaviors among the population do not reach the optimal level, one obvious way to attempt to improve the situation is to provide the information to encourage the population for adopting the health behaviors.

In case of vaccination, information provision has a great potential to increase the take-up of vaccination, especially in places where one of the main perceived barriers is the lack of knowledge on the vaccination schedule, as is the case in Adamawa state.

However, the effectiveness of information provision on the vaccine take-up might differ, depending on the type of information provided. One study provided the information on the benefit of tetanus vaccines to caregivers in India and they found the strong effect of the information provision on the vaccine take-up. The effectiveness of gain-framed and loss-framed messaging was statistically identical in their study. On the other hand, salient information, such as fear appeals, might be ineffective or it can even backfire. The investigators found, in the previous project, that in Jada Local Government Area, fear appeals intervention backfired on the tetanus-toxoid vaccine take-up among women who never received the vaccine.

If caregivers are not aware of the vaccination schedule as found in MICS 2016/2017, simply providing the information on the next vaccination schedule can be effective. Recent technological advancement makes it easy and cost-effective to send the reminder through SMS message.

Although SMS (Short Message Service) reminders are found to be effective in affecting one-time vaccine take-up, this intervention should be accompanied with the provision of more fundamental information, which can induce the repeated vaccination behaviors, to make the effect of intervention sustainable. This study proposes to provide fundamental information, which informs respondents the overall vaccination schedule, as well as tailored information, which informs where their children are in the vaccination schedule. The investigators hypothesize that, once respondents understand the overall vaccination schedule, it is easy to comprehend when and how many times more they should visit the clinic, instead of fully relying on the supply-side intervention such as SMS reminders.

Inclusion Criteria:

• women with a child 12 months old or younger

Exclusion Criteria:

• exclude women who do not have a child 12 months or younger