Overview

Any SNOMED CT subsets, subset used to code COVID-19 data , should be designed based on its purpose and the context in which they it will be used, and other specific usage requirements.

To make the process of planning and designing your SNOMED CT subsets more efficient and internationally consistent, we recommend the following three steps.

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1. Remove any concepts that are not required for your use case
2. Add any concepts missing from the subset that may be required for your specific use case;
3. Remove any concepts that are not included in the SNOMED CT versioned edition being used. This may involve
   
   • Checking the effective time of each international concept to ensure that it is less than or equal to the International Version used by your local SNOMED CT edition
   • Checking that any extension concepts are published in the SNOMED CT edition you are using
4. Add any concepts missing from the subset that may be required for your specific use case;
5. Ensure that your subset aligns with best practice principles for subset creation. 
   • For example, this may involve removing checking that all members of your subset that are supertypes or subtypes of other membersthe subset belong to a single hierarchy (in most cases), and that no two members subsume each other (in most cases).
   • For more information, please watch our e-learning presentation on this topic -   Subset Creation Principles.

Unpublished Content

Please note that the subsets in this guide may include some unpublished content that is planned for a future SNOMED CT edition. This content should not be used until it has been officially published, as we cannot guarantee that the identifiers or terms will not change. For this reason, these unpublished concepts are not included in the downloadable versions of the subsets. Unpublished concepts are included in this guide to assist with planning (e.g. planning of national extensions).

Throughout this guide, unpublished Unpublished content is shown in this guide using grey, italic font on a pink background, as shown in the example below.

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