Review Article

Integration of public health policies as a means of strengthening primary healthcare: A case study of five countries and their healthcare integration strategies

Ilona Matthew, Michelle Viljoen, Jane McCartney

Received: 10 June 2025; Accepted: 19 Feb. 2026; Published: 10 Apr. 2026

Copyright: © 2026. The Authors. Licensee: AOSIS.
This work is licensed under the Creative Commons Attribution 4.0 International (CC BY 4.0) license (https://creativecommons.org/licenses/by/4.0/).

Abstract

Background: Primary healthcare (PHC) is a crucial entry point for health prevention and continuity of care. The public health sector faces challenges in providing equitable, accessible and comprehensive care, particularly those affected by non-communicable diseases. The current rise in the burden of disease is a present-day reality, threatening population health outcomes and placing strain on the health system.

Aim: This review assessed how integrating healthcare strategies into public health policies contributes to improving the PHC model in South Africa.

Setting: This review assessed the implementation of healthcare integration strategies in low- and middle-income countries (LMICs).

Method: This review mapped World Health Organization (WHO) policy documents, South African NCD health policies, and peer-reviewed literature retrieved from electronic databases PubMed and Google Scholar, covering the period from 2000 to 2024. The search focused on evidence from LMICs on how health interventions, through innovative and integrated care models, can strengthen primary care systems to address existing challenges.

Results: The findings from the country case studies suggested that implementing integrated public health policies to strengthen primary care could reduce health inequalities among the identified disadvantaged communities and improve health outcomes. Integrated models of care strengthened service coordination, improved continuity of care and enhanced accessibility of health services at the community level. Reducing health inequalities is not achieved by policy design alone, but by the extent to which integration is supported through governance, financing, workforce and system-wide coordination.

Conclusion: An integrated approach may help to bridge the gap between public health policies and primary care.

Contribution: Insights from this review will inform evidence-based recommendations for policymakers to reorient and redesign PHC to promote integrated and continuous care.

Keywords: primary healthcare; public health policies; public health interventions; strengthening primary care; equity; non-communicable diseases; NCDs.

Introduction

South Africa has a dual healthcare system, whereby 84% of the population uses public healthcare facilities. This means that, because of the high cost of private healthcare, approximately 54 million South Africans depend on an overburdened and understaffed public healthcare system.¹ The current South African system disadvantages those with the greatest need at a disproportionate level, limiting their access to healthcare services and resulting in suboptimal health outcomes.² In contrast, the private health sector employs approximately 80% of the country’s doctors and specialists. The country’s rationale for dismantling this dual system is to introduce a National Health Insurance (NHI) to achieve Universal Health Coverage (UHC).³

South Africa is further challenged with a quadruple burden of disease (BoD).⁴ With a constant increase in cardiovascular and cardiometabolic non-communicable diseases (NCDs), there is a combined overlap of consistently high levels of mother and child deaths, human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) intensified by tuberculosis and extreme violence and injuries. Given the combination of these health challenges and population growth, the health profile of the South African population has undergone a profound transformation since the country’s first democratic election. The growing burden of NCDs in South Africa will have damaging health outcomes for the population, as it places significant pressure on the health system.⁵ Deaths as a result of cardiovascular diseases (CVD) and NCDs are presented by the Institute for Health Metrics and Evaluation (IHME) from the Global Burden of Disease study (2021). The study revealed an increase in deaths from CVD and NCDs over a decade from 2008 to 2018. Statistics South Africa recently observed similar upward trends, indicating that over a decade, deaths from CVD have increased at a steady rate, from 12.9% in 2008 to 17.6% in 2018, and deaths from NCDs increased by 58.7% over 20 years from 1997 to 2018 (Figure 1).^6,7

FIGURE 1: (a) Institute for Health Metrics and Evaluation reveal an increase in death from noncommunicable diseases and cardiovascular disease over a decade (2008 to 2018) and (b) Statistics South Africa observe similar trends over two decades (1997 to 2018).

Primary care and public health

The escalating BoD is forcing the transformation of primary care. Traditionally, primary care is centred on individualised treatment, in which the first interaction with the healthcare system is geared towards addressing immediate health issues as they arise, rather than proactively preventing illness. In contrast, public health interventions adopt a broader perspective, prioritising disease prevention and health promotion.⁸ Where the functions of primary care and public health operate as separate entities, it speaks to an antiquated disease model as it does not meet or address the evolving needs of the individual, the community and the country’s ever-burgeoning population.⁹ This health model often faces challenges, like limited resources, fragmented service models and an increase in the prevalence of NCDs that disproportionately affects disadvantaged communities. Coupled with the epidemiological shift, the revision of the healthcare model plays a significant role in treating and preventing diseases, thereby relieving the burden on both secondary and tertiary facilities. As such, primary healthcare (PHC) is vital for delivering essential services in South Africa, particularly for disadvantaged and low-income communities.

Healthcare policies

The World Health Organization (WHO) prioritises equity, building capacity, delivering comprehensive services and implementing early interventions to strengthen PHC and achieve UHC.⁹ The WHO believes that more comprehensive PHC, through integrated services, should reach everyone. To achieve that, a strong foundation of public health policies is necessary within the realm of PHC to improve both functions (of population and individual) synergistically and holistically, which is a massive challenge for any country. Furthermore, to achieve the objectives of UHC, essential public health functions need to be strengthened by reducing health risks and threats.¹⁰ By doing this, countries can more effectively address the challenges posed by NCDs and ensure equitable access to health services for all. Incorporating a public health framework into primary care can greatly enhance overall population health. The strategies for successfully integrating primary care and public health must consider the current healthcare infrastructure, along with its needs, available resources, limitations and the inequities present within the system.⁹

South Africa

The right to health is enshrined in Section 27 of the South African Constitution, and its implementation is mandated by the National Health Act of 2003, which oversees PHC services with a mission to prevent illness and promote health.¹¹ The country’s public health policies are developed to ensure the wellness and safety of the population. Non-communicable diseases have a significant global impact, causing a large percentage of deaths worldwide and disproportionately affecting low- and middle-income countries (LMICs), defined based on the economy of a country. With an escalation in lifestyle diseases, this integration of primary care and public health is necessary to reduce the burden of NCDs within communities, improve health and reduce unnecessary costs to the health system.⁹

South Africa’s healthcare infrastructure has several shortcomings, indicating that the health system is ill-prepared to address the quadruple burden.¹¹ Greater emphasis should be placed on the development and enhancement of PHC. The government has introduced several campaigns to promote healthy lifestyles. The Strategic Plan 2013–2017¹² and, subsequently, the National Strategic Plan (NSP) 2022–2027¹³ were developed to prevent and control NCDs through proper nutrition and physical activity. Both these plans recognise the importance of reducing the prevalence of NCDs, strengthening the health system and providing a framework for improving the country’s health surveillance and monitoring. The strategic plans aim to address the burden; however, with changes in the country’s epidemiological profile, the focus and approach of the more recent plan had to be amended.¹³ As outlined in the latest NSP, it is evident that the earlier strategic plan had ambitious goals.¹³ The consequence is that targets were not achieved because of resource constraints, fragmented implementation of national policies not integrated at a provincial level, inadequate surveillance resulting from data gaps and the ever-persistent socioeconomic barriers that created challenges when attempting to address the risk factors associated with NCDs.

The aim of this review is to look at practical strategies and successful initiatives employed by selected LMICs that can be used to enhance health systems at a primary care level based on the gaps identified in their policies and plans. When analysing initiatives and best practices successfully implemented in other countries, pragmatic approaches can be adapted or implemented in South Africa to strengthen the PHC model, thereby reducing the gap between primary care and public health.

Methods

The review followed the Arksey and O’Malley framework that uses a five-stage approach: Identifying the research question, identifying relevant studies, selecting the studies and country, data collection and summarising the results.¹⁴ It mapped existing literature, including full-text articles in English published between 2000 and 2025, specifically those addressing PHC strengthening in LMICs.

Research question

The research question for this study was: How can public health policies and innovative practices strengthen PHC to promote equity?

Identifying relevant studies

A search strategy was employed across multiple electronic databases, including PubMed and Google Scholar. The keywords used in the search strategy include ‘primary healthcare’, ‘primary health care’, ‘strengthening of primary healthcare’ and ‘public health policies’. Additional sources included manual searches of key policy documents, journals and reports from relevant organisations such as the WHO and South African health agencies. The search was conducted iteratively to refine the scope, incorporating additional search terms, ‘public health interventions’, to ensure completeness and capture relevant studies.

Study selection

The review mapped WHO documents, South African NCD health policies and literature from electronic databases PubMed and Google Scholar, from 2000 to 2024, from LMICs, on how health interventions, through innovative and integrated care models, can strengthen primary care systems to address existing challenges. The initial search yielded results that were screened based on article titles and abstracts. Inclusion criteria were articles that discussed PHC strengthening interventions, studies conducted in LMICs, publications published between January 2000 and December 2024, and full-text articles available in English. Exclusion criteria were articles not addressing PHC strengthening interventions, studies conducted outside LMIC settings and inaccessible full-text articles.

Country selection

Rwanda, Ghana, Thailand, Cuba and Brazil were included as case studies, as these countries share a history of inequity in resource-constrained settings, commitments to UH and challenges with the NCD burden. These five countries are classified as LMICs, similar to South Africa, where indicators such as healthcare expenditure, population size, poverty rate and Gini coefficient are compared. The five countries have demonstrated improved access to and integration of PHC within expanded health systems and financial protection, all of which offer relevant lessons for South Africa as it seeks to reform its own PHC system under a new NHI policy.

Data collection

The information collected from the literature included criteria to satisfy geographic focus, type of intervention, policy impact and equity-related outcomes. All the extracted data were systematically organised and managed using structured data management matrices to ensure consistency and transparency across all the sources. The analysis followed a comparative qualitative synthesis approach, whereby the country case studies were coded according to shared domains, including models of care, system integration, primary care strengthening mechanisms, and equity dimensions. Patterns, convergences and divergences across cases were identified through iterative analysis, enabling comparisons and interpretation of how integrated interventions influenced primary care systems and health equity outcomes.

Review findings

The initial search yielded 9469 results. After removing duplicates, 9385 unique article titles and abstracts were screened. Based on these criteria, 6780 articles were excluded. The search was updated in January 2025 with additional search terms, yielding an additional 1795 articles. Ultimately, 112 full-text articles were reviewed and appraised. From these, five LMICs addressing health system strengthening were selected as case studies, with 19 articles meeting the inclusion criteria. An additional 15 policy framework documents and five South African articles were manually identified, bringing the total resources to 39. Figure 2 presents the process of how the articles were identified, screened, excluded and selected based on the eligibility of the search criteria.

FIGURE 2: Policy and article identification, screening and selection for inclusion in the low- and middle-income countries review.

Twenty-four (n = 24) articles, published between January 2000 and January 2025, were identified as interventions that strengthen PHC in LMICs and were included in the review. Six studies reported findings from LMICs (25%), with the remainder integrated from countries Brazil, Ghana, Thailand, Cuba, Rwanda and South Africa (Table 1).

To guide the analysis of health system strengthening in the selected LMICs, this review applied WHO’s health system building blocks framework. The framework uses six key components: health workforce, health information systems, service delivery, access to essential medicine, health financing and leadership or governance. Anchoring the forthcoming analysis in this framework provides a structure for comparing strategies and challenges across the countries, with an example providing perspective.

The findings, presented in Figure 3, outline intervention strategies, challenges encountered, lessons learnt and pragmatic approaches that can be adapted or implemented in South Africa to strengthen the healthcare system and reduce the gap between primary care and public health. To enhance the relevance of the lessons, each approach was mapped to specific challenges currently facing the South African health policy. For example, difficulties in integrating community health care workers (cHCWs) with similar obstacles encountered in other LMICs and the approaches used to address these challenges could inform local South African debates. In addition, bottlenecks in referral systems and patient data management are addressed by transferable lessons in health reforms, as described in the case studies. By pairing each lesson and approach with an ongoing policy debate or an identified implementation gap in South Africa, these findings can be applied in a practical context.

FIGURE 3: Summary of health system strengthening in primary healthcare in selected low- and middle-income countries.

FIGURE 3 (Continues…): Summary of health system strengthening in primary healthcare in selected low- and middle-income countries.

Implications and recommendations

World Health Organization Strategies for Health System Strengthening³⁴ and Integration⁹ outline action steps that countries can implement in their respective areas. Full integration of the WHO’s recommended strategies may not be feasible in many countries; however, the strategies are designed to be adaptable to different health systems. Table 1 presents case studies in which LMICs have implemented various strategies, identified challenges, lessons learnt and practical opportunities that can be applied in South Africa. Evidence demonstrates that several LMICs have integrated various aspects of these strategies into primary care, achieving meaningful health outcomes; innovative care models have been identified as effective in strengthening their PHC systems. Building on insights drawn from international experiences, applying these findings to the South African context reveals both opportunities and limitations in the current PHC landscape.

South Africa: Practical opportunities and limitations

The foundation for enhancing primary care in South Africa lies in promoting equity; however, healthcare gaps persist in low-income and rural areas. PHC currently operates as a sub-programme within provincial budgets and is funded through designated allocations for various health services.²⁵ Healthcare is delivered through primary care facilities, community health clinics and outreach teams. The country has implemented action steps that benefit the community, and current initiatives reveal the country’s approach to addressing the NCD burden through developing frameworks, health promotion, strengthening systems and community engagement.¹³ The initiatives can enhance care models by placing a greater emphasis on the infrastructure and workforce at a primary care level. Disease-specific programmes, like those for HIV and/or AIDS, have demonstrated much success. However, very few of the initiatives that exhibited success are fully leveraged across the country or in an integrated manner; instead, the programmes operate in isolation.

Strategies and actions to integrate primary care into public health

Incorporating a public health framework into primary care can greatly enhance overall population health. Strategies for successfully integrating primary care and public health must consider the current healthcare infrastructure, along with its needs, available resources, limitations and the inequities present within the system.⁹ Strategies for integration, as encouraged by the WHO, and practical steps South Africa should consider to strengthen its PHC system are presented in Table 2.

Enhancing community-based services: South Africa currently uses cHCWs in many provinces, but with limited financial support, vague role clarity and uncertain employment, while recognition and support vary.³⁵ Building on existing programmes can expand the deployment of cHCWs and provide essential services, particularly in disadvantaged areas. This approach has been practical in countries like Ghana, Rwanda and Brazil.

Promote community engagement: Engaging communities in health planning and decision-making can improve the relevance and acceptance of health interventions. Community participation has been a key factor in the success of PHC initiatives in many countries.³⁶

The South African government can address inequities and improve access to essential health services by implementing health strategies that specifically focus on allocating resources to identified disadvantaged areas. The Community-Oriented Primary Care programme integrates cHCWs into PHC teams to deliver preventive care and help manage risk factors.³⁷ The training of cHCWs was explored within the community of Khayelitsha, Cape Town, South Africa, whereby community members were theoretically and practically trained to conduct the necessary screening to identify high-risk individuals for CVDs.³⁸ As observed in other countries, many challenges were experienced during recruitment and training, like language barriers, resource constraints, training duration and knowledge retention. However, with enhanced knowledge and skills, community workers were empowered and trained to prioritise urgent cases requiring immediate intervention. Routine screening programmes are now conducted at certain PHC sites, and cHCWs have been employed through local non-profilt organisations (NPOs). This type of programme could address the entire BoD across South Africa, particularly in under-resourced areas, and integrate it into other initiatives, emphasising preventive care.

Enhance health information systems: Technology integration has vastly changed how we communicate, collect and store information. Smartphones and mobile applications not only provide access to digital health services and solutions but also enhance data management. Developing robust health information systems can improve data collection and analysis, facilitating better decision-making and resource allocation. Digitisation of PHC services can enhance efficiency and patient care.³⁶

All the country case studies highlighted the necessity of data collection, monitoring and evaluation to improve the efficiency of the interventions. With continuity of patient care in mind, there is a disconnect in South Africa between how patient clinical data are collected at a PHC level and how the same patient information is collected at a secondary or tertiary hospital level. Currently, clinicians at secondary or tertiary levels in South Africa cannot access the same patient’s information when they attend the PHC facility.³⁹ An improved health information system can better capture and track health outcomes, thereby supporting informed decision-making. Furthermore, collection and analysis frameworks can also monitor progress and ensure accountability.

Implement integrated care models: By adopting a model similar to Brazil’s Family Health Strategy (FHS)²⁶ (Figure 4), South Africa can form multidisciplinary teams to deliver comprehensive care specific to a community’s needs. This would include integrating preventive care, treatment and health promotion services.

FIGURE 4: Brazil’s family health strategy depicting the health team structure.

Strengthening health i nfrastructure and workforce: Building multiple healthcare teams means a significant investment is necessary to strengthen health infrastructure and workforce. This investment must include training and retaining health professionals, improving health facilities and ensuring the availability of essential medicines and equipment.³⁶ A strong foundation for a primary care system should not only address illness but also actively promote health and prevent disease. When strengthening the capacity and competence at PHC facilities, HCWs must be fully equipped with the necessary skills and resources to achieve health promotion and prevention. PHC facilities are the primary point of contact and must be fully equipped to offer a comprehensive range of health services, including preventive and curative care, as well as rehabilitative care when necessary. Considering this, a robust PHC system requires a skilled workforce and adequate infrastructure.²⁵

Drawing on global examples from countries such as Thailand and Brazil, it is evident that strengthening primary care is crucial for achieving UHC, enhancing health outcomes and ensuring system sustainability.

Secure sustainable financing: Financing is political, and policymakers can allocate or earmark a larger share of the budget for PHC. The benefits are evident in the substantial improvements in PHC across many countries. Yet, despite its high priority, it is constantly constrained by a lack of infrastructure, qualified staff and financial resources.⁴⁰ As noted in the Thailand finance model (Figure 3), it is advisable to explore different financing options. For example, increasing sin taxes on alcohol and tobacco products can provide additional revenue that can be allocated to PHC. However, revenue from sin taxes can be volatile, depending on consumption levels, and may also adversely affect employment in related industries. There also remain challenges whereby the revenue may not be ring-fenced for health purposes, leading to misallocation or underfunding of PHC services. Collaborations with various stakeholders and the private sector may also provide financial support for PHC initiatives. Therefore, the effectiveness of these opportunities depends on their formal adoption and integration into national health policy, ensuring sustained implementation and systemic impact.

Recommendations for South Africa to integrate public health policies

To ensure comprehensive integration, health policies should:

• Prioritise healthcare expenses for vulnerable populations and disadvantaged communities. To ensure a range of services and care, the primary care workforce structure should be reconsidered, and healthcare interventions must be tailored to address the needs of communities, as shown in the Brazil case study.
• Ensure that priority be given to funding healthcare at targeted facilities, increasing the number of HCWs and improving the infrastructure in communities lacking these resources. With this targeted approach specific to communities, current disparities may be reduced, and healthcare facilities in the identified areas would also be able to offer a more comprehensive range of healthcare service delivery and care.
• Advocate programmes that promote the placement of cHCWs and relevant training in disadvantaged communities in order to improve access to primary care. The placement establishes a constant and trustworthy connection between the healthcare system and the local population, thereby promoting equity and accessibility.
• Promote health education. Government-led initiatives can foster widespread health literacy projects and campaigns that empower individuals, particularly those at higher risk, to engage in preventive health actions against NCDs. Integrating these initiatives into primary care services would enable a more successful campaign, as the scope and effectiveness of the projects could be greatly enhanced. Investing in human resources and training of community members builds and strengthens capacity, provides quality service delivery and is sustainable over a long period.
• Encourage ongoing development programmes that emphasise health promotion and the prevention of diseases like NCDs. The programmes should empower staff and provide healthcare policymakers with strategies to promote healthy lifestyles and healthy eating behaviours and, ultimately, alleviate the risk factors associated with NCDs.
• Promote the use of integrated service models. Patient visits should allow NCD screenings and, at the same time, provide mother-and-child care, wound care, mental health services and communicable disease treatments at primary care facilities. This collaborative approach reduces referral delays, improves health outcomes and enhances patient satisfaction. For example, the Chronic Dispensing Unit in the Western Cape and the Central Chronic Medicines Dispensing and Distribution programme across the country have facilitated access to medication for stable patients. With the implementation of chronic disease management initiatives at the primary care level and backed by policy support, improved programmes can assist patients in effectively managing their disease conditions through regular check-ups, encouraging compliance with all chronic medicines along with positive reinforcement of lifestyle changes. These programmes are central to managing the burden of disease and reducing hospitalisation and associated healthcare costs.
• Establish standardised care practices for HCWs at PHC facilities. This will ensure reliability and consistent treatment across all services and facilities. Policies should enforce these ‘best practice’ approaches that improve patient care and guarantee that patients have access to services that are crucial to managing and treating NCDs effectively.
• Create a more robust referral network. An improved network can provide feedback mechanisms that enable patients needing specialised care to be smoothly directed to secondary and tertiary healthcare facilities. Supporting these networks through a health policy can enhance care continuity and improve health outcomes.
• Dictate that routine screenings for NCD risk factors should occur within primary care settings, mainly targeting communities and populations identified as being at higher risk. Early identification of risk factors enables timely interventions that can prevent or delay disease progression.
• Facilitate early intervention. Facilitate the implementation of various campaigns to support early intervention, such as telehealth services. HCWs can monitor patients remotely, alleviating some of the pressures and reducing the number of patients currently seen at physical facilities. This method is particularly favourable for the continuous monitoring of NCDs.

Points to consider for the successful integration of public health policies into primary care in South Africa

• Political commitment and policy alignment are critical for integration to work.
• Strong leadership is essential for the successful implementation of several programmes or campaigns and to provide the necessary foresight and guidance.
• Partners are vital. Engaging with the private sector and establishing partnerships with NPOs and private entities at both local and national levels can attract additional resources and foster innovative healthcare delivery models, thereby advancing primary care equity, particularly in disadvantaged areas.
• Invest in infrastructure, especially the provision of essential diagnostic tools and the educational resources necessary to promote effective health and disease prevention. Health policies must prioritise improving infrastructure in primary care settings to ensure optimal service delivery.

Limitations

The study had several limitations that should be noted. It relied on published government-led public health strategies and English-language published literature, which may limit the scope of insights. The selected timeframe for this study, 2000–2025, may not fully capture healthcare developments or projects that extend beyond this period. Additionally, regional and community-specific challenges were not explored in depth, and a more detailed analysis could offer valuable insights into local variations.

Conclusion

Across the reviews, integrated models of care were consistently characterised by strengthened service coordination, improved continuity of care and enhanced accessibility of essential health services at the community level. The structural and organisational changes were linked to more coherent patient pathways, reduced fragmentation between preventive and curative services and greater alignment between population-level policy objectives and frontline service delivery. Strengthening primary care through the integration of public health policies is vital to addressing the burden of NCDs in South Africa. The evidence further suggests that integration enables primary care systems to respond more effectively to complex and chronic health needs, particularly in settings where communities experience compounded social and economic vulnerabilities. The sustained focus should be on equity, strengthening capacity, providing a comprehensive range of services at the primary care level and promoting early intervention. Healthcare policies should integrate campaigns to enhance and improve PHC, particularly in identified and disadvantaged communities. Through this integrated approach across several campaigns, countries aim not only to enhance population health outcomes but also to minimise inequities. A strategic policy framework that emphasises these key areas will empower the healthcare system to address both, current challenges and future health issues, ensuring that primary care remains a strong pillar of public health infrastructure. More importantly, the findings demonstrate that the potential to reduce health inequalities does not derive from policy design alone but from the extent to which integration is institutionally supported through governance structures, financing mechanisms, workforce development and system-wide coordination.

Acknowledgements

This article is based on research originally conducted as part of Ilona Matthew’s doctoral thesis titled ‘Improving access and reducing the gap between public health policies and primary care: An analysis of non-communicable diseases in the Cape Town Metropole’, submitted to School of Pharmacy, Faculty of Natural Sciences, University of the Western Cape. The thesis was supervised by Michelle Viljoen and Jane McCartney. The thesis was reworked, revised and adapted into a journal article for publication. The original thesis is ongoing and is currently unpublished and was not publicly available online at the time of publishing this article.

The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article.

Ilona Matthew: Conceptualisation, Data curation, Formal analysis, Investigation, Methodology, Project administration, Resources, Software, Validation, Visualisation, Writing – original draft. Michelle Viljoen: Methodology, Supervision, Writing – review & editing. Jane McCartney: Methodology, Supervision, Writing – review & editing. All authors reviewed the article, contributed to the discussion of results, approved the final version for submission and publication and took responsibility for the integrity of its findings.

This article followed all ethical standards for research without direct contact with human or animal subjects.

This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

Data sharing is not applicable to this article as no new data were created or analysed in this study.

The views and opinions expressed in this article are those of the authors and are the product of professional research. It does not necessarily reflect the official policy or position of any affiliated institution, funder, agency, or that of the publisher. The authors are responsible for this article’s results, findings, and content.

References