Blockchain technology, a practical solution to vaccine verification systems



Vaccine verification is critical to any country’s ability to control the course of the pandemic. Having a reliable, secure and accurate verification system gives government, businesses, schools or any other institution the ability to assess the safety of indoor and outdoor gatherings and provides real-time statistics on vaccinated populations. Although many countries around the world have developed their own vaccine verification systems, often derived from previous contact tracing applications, developing a reliable, secure and accurate system remains a challenge. This is in part due to the data storage and retrieval protocols. Another major obstacle is information sharing, especially considering how important it is for vaccine verification systems to be accepted across national and international borders.

Dr Tom Frieden, director of the Centers for Disease Control and Prevention from 2009 to 2017, expressed his concerns on the long-term difficulties of having multiple Covid-19 vaccination verification systems. “Its own user interface, validation, data storage, retrieval processes and security protocols will make it difficult to quickly and securely check vaccination status. For a system to work, it recommends five essential requirements.

  • Accuracy should be maintained by using a computerized immunization information system, that is, an online record of immunizations received by individuals.
  • Appropriate assurances and guarantees must be implemented to ensure the security and confidentiality of everyone’s personal data.
  • In the event of unforeseen circumstances, the possibility of using other forms of identity should also be allowed. For example, having the option of using paper vaccination records with additional personal verification, such as photo ID.
  • The system should only be used to verify immunization records and should avoid adding information about previous tests and results to avoid aggregating data.
  • And must be accessible in real time, “like when people go through airport security”.

Blockchain technology can provide a practical solution to the challenges of vaccine verification and can help meet the requirements described by Frieden. Due to the decentralized and encrypted nature of blockchain technology, the information stored in the blockchain ledger is extremely difficult to tamper with. This meets a very crucial requirement of an immunization verification system, which guarantees the security and confidentiality of personal data.

By scanning the serial numbers of vaccine shipments and storing them in a blockchain ledger, goods can be authenticated at any point in the supply chain. To understand how exactly blockchain technology solves the issue of data storage, retrieval processes, and information sharing, we can look at ‘VacciFi’, an architectural framework for Covid vaccination passports provided in a to study who reviewed a GDPR-compliant blockchain-based Covid vaccination passport.

Let’s say we apply this framework to travel. In this context, an unvaccinated person would register with their local health authority for vaccination. After registration, they would receive a vaccination ID card, which they would take to the hospital or clinic where they would be vaccinated. During the visit to the hospital, the reception will record all the necessary information about the person to be vaccinated. Information such as traveler’s name, passport number, contact number, etc. will be stored off-line due to regulations such as general data protection compliance purposes. The hospital would store two types of information on the blockchain: 1) the passport number and the generated hash of the vaccination ID and, 2) the date of the administered vaccination dose. This will generate a QR code which can be pasted on the passport and will also be shared via email as an electronic copy.

The purpose of the QR code is to verify the details and validity of the vaccination. In off-chain systems, four operations can occur: create (the right to create a new recording in the off-chain), read (the right to read and view the recording), update (the right to update update existing records) and delete (delete records). Here are the access privileges offered by different authorities based on the VacciFi framework:

Here all parties have the opportunity to read existing records and in doing so check a citizen’s immunization records. The only party authorized to create or delete the file is the vaccination authority.

While traveling, the QR code is presented by the traveler to immigration staff. When scanning the QR code, all relevant vaccination details and hash code (generated in hospital) from local off-chain storage. The hash is then verified by comparing it to the hash stored on the authorized blockchain, via a smart contract. If there is a match, the blockchain will return the validity and dates of vaccination (figure 3), thus completing the verification process.

The security associated with only QR code-based digital health evidence systems, which many vaccine passports are adopting, is of great concern. With personal data involved, any leakage or insufficient protection will raise the possibility of a complete invasion of privacy. Blockchain technology is already being deployed to fight counterfeit vaccines and scams that threaten our long-term stability.

This dilemma extends beyond vaccines. Reports of circulating fake vaccination certificates are constantly in the news, hinting at the need for more reliable technology to mitigate these unintended and deadly consequences. The World Health Organization says bogus vaccines and other malicious alternatives to bypass our vaccine verification systems “pose a serious risk to global public health.” As vaccine inequality also presents itself as a negative catalyst in our fight against Covid-19, fake vaccines are a bigger problem in poorer countries, which already have a low supply and vaccination rates.

George Connolly, President of OneLedger Technology Inc., oversaw the development of the OnePass Vaccine Passport, a scalable and secure solution blockchain-based vaccination passport. He explains in an article that these passports, issued by a medical provider, contain an individual private key for the user. With each private key there is a corresponding public key, which is stored in the blockchain ledger. Using the registry, a QR code is generated to confirm an individual’s vaccination. Users of blockchain-based passports have the freedom to decide what information they choose to disclose, such as name, date of birth and / or nationality. This strengthens the protection of privacy and encourages the creation of reliable and accurate immunization records.

While blockchain cannot resolve questions regarding the inclusiveness and fairness of vaccine verification systems, it can provide a platform for success for countries trying to implement their systems safely and with confidence. the ability to manage the flow of information in real time.


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