SACRAMENTO— Community clinics in California say they haven’t been paid for at least 1 million COVID-19 vaccine doses given since January, creating a “ massive cash flow problem ” for some and complicating efforts to retain staff.... Clinics in other states, including Michigan and Mississippi, are also awaiting payment. The delays stem from the distinct way federally qualified health centers are reimbursed for care under Medicaid, the joint federal-state program providing health coverage for low