Blockchain-Based Privacy-Preserving Vaccine Passport System

Table 1

Comparison of COVID-19 vaccine systems.

	Blockchain structure	Vaccine supply chain	Vaccination record	User privacy	Vaccination hospital privacy	Vaccination privacy	Auditable	Vaccination certificate
[7]	Public blockchain
[10]	Public chain and private blockchain
[6]	Public blockchain
[8]	Private blockchain
[5]	Public blockchain
[22]	Consortium ethereum-based blockchain
[23]	Consortium blockchain
[24]	Permissioned blockchain
China health code system	No blockchain
This study	Public blockchain and consortium blockchain

“ ” represents that the privacy protection of this attribute of the vaccine system is based on stronger assumptions, such as storing the private data in a private database off-chain or increasing the restriction of database access, thus having a higher probability of privacy leakage. “” represents that this attribute of the vaccine system is not mentioned from the open-source code or references.