Health system reconstitution syndrome: an often misunderstood phenomenon in global health practice.

The beginning of the 21st century was marked by the new definition and framework of health systems strengthening (HSS). The global movement to improve access to high-quality care garnered new resources to design and implement comprehensive HSS programs. In this effort, billions of dollars flowed from novel mechanisms such as The Global Fund to Fight AIDS, Tuberculosis and Malaria; Gavi, the Vaccine Alliance; and several bilateral funders. However, poor health outcomes, particularly in low-income countries, raise questions about the effectiveness of HSS program implementation. While several evaluation projects focus on the ultimate impact of HSS programs, little is known about the short- and mid-term reactions occurring throughout the active implementation of HSS interventions. Using the well-documented WHO framework of six HSS building blocks, we describe the evolution and phases of health system reconstitution syndrome (HSRS), including: (1) quiescent phase, (2) reactive phase, (3) restorative phase and (4) stability phase. We also discuss the implications of HSRS on global health funding, implementation, policy and research. Recognizing signs of HSRS could improve the rigour of HSS program design and minimize premature decisions regarding the progress of HSS interventions.