In our first post in this series, we took a look at what to consider when designing a vaccination credential – or digital health pass – to verify COVID-19 risk status in a way that is both validated and trustworthy. In part two, we discuss how the challenge gets even more complex when factoring in the need for a pass that works on an international level.
Harmonizing standards and comprehensive code sets
When we think about designing digital health passes for those in the US, we need to make sure we are pulling the right information from the right sources, and that the data is comprehensive enough for many use cases. Additionally, the specific data elements used to represent this information must be properly mapped to the appropriate standardized code sets.
This is particularly important regarding international travel, since not all code sets have universal adoption. For instance, the CDC’s vaccine manufacturer and name code sets (MVX and CVX, respectively) are used to refer to vaccines in the US, but not elsewhere. However, there are COVID-19 vaccines that have not been cleared for use in the US – such as China’s Sinopharm and Russia’s Sputnik V. Accordingly, they are not represented in the CDC code set.
Thus, for a pass to be used in an international context it would have to access a comprehensive code set list containing all globally acceptable vaccines. International harmonization efforts led by organizations such as the World Health Organization’s Smart Vaccination Certification Working Group and the Vaccine Credential Initiative (VCI) are keenly aware of the need for highly interoperable digital passes. For example, the VCI – a public-private coalition of which IMO is a member – has extended its vaccine code set list to include SNOMED-CT; ICD-11; the global supply chain standard Global Trade Item Number (GTIN); and the World Health Organization’s classification system of active substances (ATC).
Clinical terminology and value sets
Clinical interface terminology can help developers to group vaccines across the different code sets and create a single representation for decision-making logic. Once data has been aggregated and normalized, it can produce a complete picture of the user’s health information needed for health pass validation. Highly granular, precisely defined value sets can then be applied to the data as part of the decision-making logic to determine whether the holder of the pass meets the verifier’s entrance criteria.
In lieu of universal adoption of standardized decision-making logic across the various health passes currently being developed, entrance criteria are likely to vary depending on use case and country. For example, on May 14, 2021, the United Nations World Tourism Organization (UNWTO) released a set of recommendations for the use of vaccine passports, which suggest including not only vaccination status, but also test results and information about recovery from COVID-19 as part of a pass.
Indeed, on June 1, 2021, the European Union released its EU Digital Green Certificate to seven member states and aims to make it available to all 27 members by July. It contains three specific data elements related to previous COVID-19 history – disease or agent, date of first positive test result, and country of test. In contrast, the International Air Transport Association’s (IATA) Travel Pass provides travelers on participating airlines with a way to store and manage verifiable vaccination and test information, but does not include prior infection history. Accommodating these different requirements could be a challenge, but precisely defined value sets could be used to quickly and accurately identify the specific data elements needed to satisfy entrance criteria.
In conclusion, the rapidly changing and widely variant code environment – combined with a heterogenous landscape of entrance criteria – puts a large burden on application developers of digital health passes. Proper use of health information technology combined with good clinical terminology can dramatically improve the function and acceptability of these passes.
