WellCare's Role in the CVS-Aetna Merger. Health (4 days ago) WellCare's Role in the CVS-Aetna Merger. HARTFORD, Conn. and WOONSOCKET, R.I (October 10, 2018)—Aetna, headquartered in Hartford, Connecticut, is the nation's third-largest health-insurance company and fourth-largest individual prescription drug plan insurer, with over two million prescription drug plan members..