Blockchain technology plays a vital role in the medical industry for COVID-19 by facilitating communication between various stakeholders. Blockchain-based healthcare systems like eHealthChain, etc., have been developed over the past years to store health records securely. But most systems depend on storing data either directly on the blockchain, which is not scalable, or on off-chain storage systems, which are not completely decentralized. Also, scalability was one of the major issues in these systems, which limits blockchain technology in high-throughput, low-latency applications such as COVID-19 image sharing. Hence, in this article, a Scalable eHealthChain (SeHealthChain) is proposed that introduces a new reputation-based scalable blockchain system via a sharding scheme in the eHealthChain system. First, a novel dual-chain structure including a transaction chain and reputation chain is proposed. A modified Raft-based synchronous consensus scheme is used for the transaction chain, whereas the synchronous Byzantine fault-tolerant consensus is used for the reputation chain. This prevents attacks on both the reputation score and the associated transaction blocks. It supports a high-throughput transaction chain with tolerable generation speed. Additionally, a reputation-based sharding and leader selection technique is proposed to increase the system throughput and security level. Thus, this system enhances the throughput and security level for COVID-19 image transmission. Finally, an extensive experiment shows that the SeHealthChain achieves higher throughput and level of security compared to other sharding-based blockchain systems.

Blockchain, Healthcare applications, eHealthChain, Sharding, Reputation