To elaborate recommendations, the CDS needs the history of previously administered vaccines.
This history is made of a list of administration events, each event consisting of the date of administration and the product that was administered.
This history may contain vaccines that were administered decades ago, or abroad. These vaccines could be identified as an explicit branded product or with a vaguer description, such as “Tdap” (some vaccine with the three valences tetanus, diphtheria low dose, acellular pertussis low dose), or even “Vaccine against poliomyelitis”.
Using the most precise available information is important. Routine vaccination schedules are written based upon actual products summaries of product characteristics, and trying to reinterpret them with generic descriptions may be misleading and create a responsibility blur between the NITAG and the digitization team.
Oppositely, catchup vaccination strategies require to understand the role of a foreign or past vaccine, that is not explicit only from its code or name. The codes used must be complemented with a minimal functional description of the vaccine, characterizing the effect on the human immunity system.
The existing electronic records of vaccinations rely upon heterogeneous code systems, such as national pharmaceutical codes (PZN, CIS, CNK, etc.), regional codes (CVX, EU identifier for centrally approved vaccines, etc.) or international generic codes (ATC, ICD-11, SNOMED-CT).
To gather all of these in a comprehensive and descriptive representation, EUVABECO endorses the NUVA unified nomenclature of vaccines, supported by the International Vaccine Codes Initiative. This pivot codification, used also in the EUVABECO European Vaccination Card, is built to integrate the alignments with any code system as well as a functional description of each vaccine concept.
To elaborate the recommendations, the CDS needs the characterization of the regarded person. This characterization consists of Health, Ageing, Living conditions and Occupation characteristics, known as HALO factors.
The HALO factors are identified by the NITAGs when elaborating the vaccination schedules for their health jurisdiction. They may be extremely diverse, ranging from basic notions such as age to complex situations like living with an immunocompromised person.
When the CDS is invoked from a professional health application, it is desirable that the HALO factors are populated from the existing records. Yet, this is only partially achievable for many reasons:
Yet, these difficulties should not exclude the use of such preexisting data, at least to populate a set of HALO characteristics submitted to human review before submitting. To support this, the EUVABECO project suggests that:
The rules for the CDS are elaborated from the documentation provided by the NITAG. This documentation could itself be structured as rules, or as content that can be converted to rules. This is for example the case of the CDSi project from the US NITAG, the ACIP.
The CDSi dataset is used to produce CDS rules, as well as test profiles for compliance of CDS implementations.
Not all NITAGs will reach this level of maturity in a near future. Yet, the EUVABECO project will contribute to the emergence of this approach with the publication in a GitHub repository of a common syntax for CDS rules, as well as the rulesets elaborated during the pilot projects.