Since the Alma Ata Declaration of 1978, countries have varied in their progress towards establishing and sustaining comprehensive primary health care (PHC) and realizing its associated vision of ‘Health for All’. International health emergencies such as the coronavirus-19 (COVID-19) pandemic underscore the importance of PHC in underpinning health equity, including via access to routine essential services and emergency responsiveness. This review synthesizes the current state of knowledge about PHC impacts, implementation enablers and barriers, and knowledge gaps across the three main PHC components as conceptualized in the 2018 Astana Framework.