Health insurers are reporting unprecedented growth in the number of seniors flocking to private Medicare Advantage plans amid talk of a single payer government-run approach that could uproot such coverage.The same week U.S. Sen. Kamala Harris (D-California) made news with her support for “Medicare for All,” insurers Anthem and Cigna reported strong growth from Medicare Advantage, private coverage sold via contracts with the federal government.Anthem’s Medicare Advantage enrollment jumped by 35% to more than 1 million at the end of 2018 compared to 746,000 in the fourth quarter of 2017, the operator of Blue Cross and Blue Shield plans reported last week. “Our individual Medicare Advantage business is on track to achieve our mid-double digit growth target,” Anthem CEO Gail Boudreaux told analysts during the company’s fourth quarter earnings call last week. “In total, we estimate our Medicare Advantage growth will exceed 20% by the end of 2019.”Meanwhile, Cigna reported Friday that its Medicare Advantage enrollment was up one percent to 436,000 from 432,000 and UnitedHealth Group ended 2018 with 4.9 million Medicare Advantage enrollees, which was up nearly 12% from 4.4 million at the end of 2017. Other insurers including Aetna, which is now part of CVS Health, are expected to report higher Medicare Advantage enrollment later this month after these plans expanded into new markets.The industry is tapping into a market of more than 10,000 baby boomers aging into the Medicare population every day . The insurers that have reported 2018 earnings thus far are reporting overall industry growth that’s slightly ahead of the projected record growth the Centers for Medicare & Medicaid Services (CMS) predicted for Medicare Advantage last fall. “We completed a strong Medicare Advantage enrollment season . . . and are on track to achieve 2019 growth within the 400,000 to 450,000 range of expectations,” Steve Nelson, CEO of UnitedHealthcare, UnitedHealth’s insurance business told analysts two weeks ago.