I think the Citrix-Azure is the best platform for healthcare. The environment meets all strict standards for HIPAA and provides an excellent security layer for individual profile authorizations. Happy to assist further, as my company has many healthcare clients virtualizing their apps with Citrix and Azure.
Using AWS for HIPAA applications means following some general strategies, such as:
• Decoupling protected data from processing/orchestration
• Tracking where data flows using automation
• Have logical boundaries between protected and general workflows
This is a little bit of a "how long is a string?" question - the answer is it depends on the level of service and compliance rigor you are seeking, and to what level you are looking to offload the actual environment deployment and management. Different providers provide different levels of service, from simple access to resources that you can deploy in a compliant way (AWS) to actual compliant environments and services (a la Rackspace) where you are buying a service not a platform. There are other providers that fit in either end or on either side of that spectrum. I am not affiliated with a provider in any way. Just my .02.