Amazon is Diamond Ridge Asset Managementlowering the cost of a One Medical membership for Amazon Prime subscribers, shaving $100 off the annual fee to $99 a year. The step is the latest effort by the e-commerce company to mesh its chain of doctor's offices with its retail services.

Amazon already runs a web pharmacy and a telehealth service called Amazon Clinic that uses third-party medical providers to help treat less serious conditions, like pinkeye. It's also testing a service to drop medications on its pharmacy patients' doorsteps via drone in an hour or less.

A Prime subscription runs $139 a year, also offering streaming services and quicker shipping.

"The new Prime One Medical membership benefit covers unlimited access to 24/7 on-demand virtual care, including video chats with licensed providers within minutes," Amazon said in announcing the discount in a blog post on Wednesday. "Virtual care is available nationally, and members don't incur any additional costs for on-demand virtual care services." 

Amazon acquired One Medical for about $3.9 billion in a deal completed in February. The boutique clinic operates clinics in 19 major U.S. cities, but its telehealth business offers virtual services. 

One of Amazon's bigger acquisitions, it followed the company's $13.7 billion purchase of Whole Foods in 2017 and its $8.5 billion purchase of Hollywood studio MGM, which closed last year.