In a letter to the company, Health and Human Services Secretary Kathleen Sebelius voices concern over the rates, which take effect March 1 for many of the insurer's 800,000 individual policyholders. The Obama administration called on Anthem Blue Cross on Monday to justify its controversial new rate hikes of as much as 39% for individual policyholders, saying the increases were alarming at a time when subscribers are facing skyrocketing healthcare costs.