Allina Health and Aetna Insurance Co. enrolled about 12,000 people in coverage during the first quarter of operations for the firms' joint venture, according to a regulatory filing this month.

Membership in the new joint-venture company, which is based in St. Louis Park, was roughly split between people with coverage via employer groups and those with Medicare health plans.

Allan Baumgarten, an independent health care analyst, noted that 2019 represented a unique chance for new companies in Minnesota's Medicare market to draw some of the more than 300,000 seniors in Minnesota who had to drop a type of coverage known as Medicare Cost health plans.

"So, 6,000 is good, but definitely not great," Baumgarten said. "This was sort of a one-time opportunity to get market share in that line of business, because seniors tend to stay with their plans once they've selected a plan."

In a statement to the Star Tribune, company officials said they were "encouraged" by the enrollment thus far. The company did not say whether the tally includes employees at Allina Health System, the Minneapolis-based operator of hospitals and clinics with 29,000 workers that made coverage through the new joint venture an option for its employee health plans.

Aetna, which is one of the nation's largest health insurers, is a division of Rhode Island-based CVS Health.

During the first quarter, the joint-venture company posted an operating loss of $3.3 million on $16.7 million.

"There are always investments to start a business before you turn a profit," the company said in a statement. "While we don't comment on financial specifics, we're not seeing anything we haven't anticipated and look forward to continued growth."

Last year, the Allina-backed company received $81.5 million in capital contributions, according to a regulatory filing.

The joint venture started providing coverage during the fourth quarter to one employer. By the end of the first quarter, the tally of covered lives in employer groups grew to 6,166.

The company's Medicare coverage started Jan. 1, and included 5,977 people by March 31.

Christopher Snowbeck • 612-673-4744 Twitter: @chrissnowbeck