Final answer:
The three minimum functional standards are real-time data reporting, age-based reminders, and user training. These standards help maintain accurate and secure immunization records.
Step-by-step explanation:
Three of the 12 minimum functional standards for immunization registries are real-time data reporting, age-based reminders, and user training. Real-time data reporting ensures that health records are updated promptly, which helps in maintaining an accurate record of immunizations. Age-based reminders are necessary to prompt health-care providers and patients about upcoming vaccines based on the Recommended Immunization Schedule provided by agencies like the CDC. Lastly, user training is essential so that health-care workers can effectively use the registries and ensure the integrity and security of the data.