This article is part of the Research Topic ‘Health Systems Recovery in the Context of COVID-19 and Protracted Conflict’Health systems resilience has become a ubiquitous concept as countries respond to and recover from crises such as the COVID-19 pandemic, war and conflict, natural disasters, and economic stressors inter alia. However, the operational scope and definition of health systems resilience to inform health systems recovery and the building back better agenda have not been elaborated in the literature and discourse to date. When widely used terms and their operational definitions appear nebulous or are not consistently used, it can perpetuate misalignment between stakeholders and investments. This can hinder progress in integrated approaches such as strengthening primary health care (PHC) and the essential public health functions (EPHFs) in health and allied sectors as well as hinder progress toward key global objectives such as recovering and sustaining progress toward universal health coverage (UHC), health security, healthier populations, and the Sustainable Development Goals (SDGs). This paper represents a conceptual synthesis based on 45 documents drawn from peer-reviewed papers and gray literature sources and supplemented by unpublished data drawn from the extensive operational experience of the co-authors in the application of health systems resilience at country level. The results present a synthesis of global understanding of the concept of resilience in the context of health systems. We report on different aspects of health systems resilience and conclude by proposing a clear operational definition of health systems resilience that can be readily applied by different stakeholders to inform current global recovery and beyond.

Background COVID-19 has caused unprecedented disruptions to health, social and economic systems in countries worldwide including Ireland. Weaknesses in Public Health capacities have undermined health system resilience compounding the effects of the pandemic. The Essential Public Health Functions (EPHFs) provide a comprehensive, cost-effective approach to operationalising public health and a means to build health systems resilience. As Ireland looks to recovery, the Department of Health engaged the World Health Organization (WHO) to undertake a mapping of the current state of delivery of EPHFs to identify opportunities for improvement and support wider health system strengthening towards resilience. Methods A strategic review of the delivery of EPHFs in Ireland was conducted with respect to policy, infrastructure, service provision and coordination and integration. Findings were reported in the context of international lessons identified through experience with COVID-19 and major health system challenges within the Irish context. Results There are significant capacities present within the Irish context to support the delivery of the EPHFs though they are limited in strategic cohesion, coordination and implementation. These include a high level of Public Health expertise, an agile and resourceful workforce, a strongly engaged community and significant evidence generation and synthesis capacities. Gaps recognised included ICT infrastructure and capacity, workforce resourcing and support, pandemic planning and public health governance, visibility, legislation, strategy and resourcing. COVID-19 has led to the development and strengthening of mechanisms to leverage a whole-of-government and -society approach to health that should be sustained to tackle ongoing and future stressors. Conclusions The use of the EPHFs within the Irish setting provides a comprehensive approach to strengthening capacities for public health and enhanced population health and wellbeing.

Background The COVID-19 pandemic has exposed Public Health system weaknesses due to chronic underinvestment in Public Health. In this context, Essential Public Health Functions (EPHFs) have been revitalized as an integrated, cost effective and sustainable approach to operationalising Public Health. The World Health Organization's recent position paper on building health systems resilience towards universal health coverage and health security recommended investing in EPHFs as a key mean for countries’ health systems recovery and transformation during COVID-19 and beyond. There is a need for conceptual and operational clarity of EPHFs to support countries to build back better, fairer and more resilient health systems. Methods A rapid review of peer-reviewed and grey literature regarding the EPHFs was conducted to identify different actors’ understandings of EPHFs and key lessons of applying the EPHFs at the global, regional and national levels, in order to identify the added value and key enablers to operationalising EPHFs. A crosswalk analysis of different authoritative lists of EPHFs was conducted to develop a common list of EPHFs as a reference for countries in response to Public Health challenges. Results A consolidated list of 12 EPHFs derived from the crosswalk analysis of different authoritative lists is presented, underpinning the consideration of health systems components and pressing health challenges. Six key enablers are identified from evidence and experience. These enablers are fundamental for countries to build holistic and strong Public Health capacities. Conclusions The EPHFs provide a clear and integrated framing to operationalise Public Health in countries that can be adapted to country contexts to build resilience. Health authorities and other Public Health stakeholders must seize the opportunity brought by COVID-19 recovery to continue advocating for and strengthening Public Health as a priority in health systems’ reconstruction and reform.