As part of the response to COVID-19, a coalition of health and technology leaders has created the Vaccination Credential Initiative (VCI; https://vci.org/) . VCI’s goal is to provide a trusted and verifiable copy of vaccination records, or other COVID-related laboratory test results. This will be accomplished by using the SMART Health Cards framework ( https://smarthealth.cards/), which works with both digital and paper workflows. The SMART Health Cards framework does not specify the clinical content contained within. The purpose of the proposed FHIR Implementation Guide is to do just this: describe the contents of a FHIR Bundle that is contained within a Health Card. The development of this IG is part of the VCI working group (n.b. that this is not a HL7 Work Group), which includes representatives from EHR vendors, large health systems, testing laboratories, and technology companies. We are working closely with experts from these organizations to inform the content and structure of the IG. The resulting product of this effort will be a FHIR IG that Issuers of Health Cards can use to build and validate their implementation, and Verifiers of Health Cards can use to design their verification process.