Amazon Clinic does not yet accept health insurance, so competitors are protected (a bit) in the interim. The addressable market is big, and there is plenty of competition already. WELL still is more focused in Canada but the US offers lots of potential. VMD has most of its revenue in the US and may be more vulnerable. But, like with other sectors, AMZN can be a formidable competitor. It is something to watch but not yet worry about.
Authors of this answer, directors, partners and/or officers of 5i Research and/or affiliated companies have a financial or other interest in AMZN.