When patients are eligible to take more than two types of vaccines simultaneously, it's surprisingly a struggle for nurses to work out the times and dates that could minimize the patients' trips to the hospital for the next vaccine shots. Different types of vaccines require different time intervals between the doses. The problem causes many time-consuming challenges: nurses must manually document all vaccines administered to avoid errors or missed doses, communicate and get help from each other to determine the proper dates for the following shots, etc. All of that manual work can be automated by the patient_vaccine_program to remove one of the hassles and uncertainty nurses face every day.