CVS' retail segment significantly outperformed the company's expectations in the fourth quarter as demand for tests skyrocketed with the spread of the omicron variant, as did demand for vaccine boosters. Total medical membership at Aetna, the company's health plan, was 23.8 million at the end of 2021, up from 23.4 million at the end of 2020. Thanks to the results, CVS affirmed its earnings guidance for 2022 of between $8.10 and $8.30 in earnings per share. The company did adjust its cash flow from operations estimate to between $12.5 billion and $13 billion.