Mobile Health Solutions Combined With Behavior Change Approaches to Improve Vaccination Coverage and Timeliness in Bangladesh: a Cluster Randomized Controlled Trial

Inclusion Criteria

Inclusion Criteria: 1. You are the infant's caregiver (mother, father, or legal guardian). 2. The infant is less than 4 weeks (28 days) old at the time of enrollment. 3. You reside within the jurisdiction of the designated community health center and have no plans to move within the next 12 months. 4. Depending on your assigned group, you can do one of the following: * You can read Bengali SMS messages yourself. * You can receive support from a family member living with you who reads Bengali aloud. (Note: For the voice call group, literacy is not an issue.) 5. You understand the content of this study and have completed the required informed consent form. Exclusion Criteria: 1. Caregivers of children aged 4 weeks or older at the time of enrollment 2. Children who have received any vaccine other than BCG or polio at birth 3. The caregiver plans to move out of the study area within the next six months. 4. The caregiver does not want to receive the vaccination at the intervention health center. 5. The caregiver (father, mother, or other family member) does not have a phone.