Abstract: According to the invention, a system for determining whether to guarantee payment to a health care provider for administering a vaccination to a patient is disclosed. The system may include a computer which receives, from a provider interface, a check-in message which includes biographical information of the patient and insurance information of the patient. The computer may also determine, based on the biographical information, a vaccination that the patient should receive. The computer may further determine via a rules engine, and based on the insurance information, a likelihood that an insurance claim for the vaccination would be approved. The computer may additionally determine, based on the determined likelihood, whether to guarantee payment to the health care provider for administering the vaccination. The computer may moreover send an eligibility message to the provider interface, where the eligibility message includes an indication of whether payment for administering the vaccination is guaranteed.