The COVID-19 pandemic underscored the crucial role of smartphones in disseminating health information, particularly during lockdowns and social distancing [1]. This period saw a surge in pandemic-specific mobile apps aimed at managing public health crises [2]. However, their success depended on widespread adoption and public trust, especially when handling sensitive medical data and personal risk assessments [3]. Developers faced the challenge of balancing usability, security, and rapid deployment, while also addressing critical concerns regarding data protection and user control.

To tackle these challenges, the COMPASS initiative (Coordination on Mobile Pandemic Apps Best Practice and Solution Sharing [4]) was established as part of Germany’s Network University Medicine (NUM) program. From the outset, COMPASS aimed to create a structured framework for developing, evaluating, and deploying pandemic apps, leveraging expertise in science, technology, and legislation. Its core objective was to ensure that pandemic apps were effective, interoperable, and research-ready, facilitating their rapid and optimal use in future health emergencies.

A key challenge was the absence of clear legal, regulatory, and technical guidelines for integrating app-collected data into COVID-19 research while ensuring compliance with privacy standards [5]. This gap created uncertainties in assessing the effectiveness of these apps and limited their utility for stakeholders such as researchers, clinicians, and public health authorities.

Through interdisciplinary collaboration between scientists, industry, and academic partners, COMPASS developed an open-source, modular technology platform that allows for the rapid adaptation and reuse of pandemic apps. The initiative provided best practice guidelines, standardized app components, and frameworks to ensure compliance, usability, and security. Its approach bridges the gap between technological innovation and real-world health care application, demonstrating how mobile health (mHealth) solutions can be effectively integrated into pandemic management.

This paper highlights the interplay of key components within the COMPASS framework, emphasizing its strategic approach to coordinating mHealth solutions. By integrating best practices in app development, governance, interoperability, and data security, COMPASS establishes a sustainable model for future health crises. Beyond Germany’s NUM program, its findings contribute to global efforts in advancing digital health strategies for pandemic preparedness.

The COMPASS approach integrated the expertise and experience of 9 university hospitals and external partners in the development and use of pandemic apps. It established a collaboratively coordinated and standardized platform to ensure the legally compliant and interoperable deployment of such apps. Table 1 provides an overview of all 9 participating institutions, including their commonly used abbreviations and the affiliations of the authors contributing to this paper.

Table 2 provides a summary of the COMPASS project, outlining its primary objectives, duration, key participants, development principles, focus areas, sustainability efforts, and accessibility. This overview highlights the core components of the initiative, offering a quick reference to its scope, structure, and strategic direction.

Despite being developed 4 years ago, smartphone-based medical apps remain in high demand, largely due to the growing emphasis on patient-reported outcomes (PROs) [6], which COMPASS actively supports. Studies highlight significant discrepancies between health care professionals’ assessments and patients’ actual symptom experiences [7], emphasizing the importance of PROs. Their impact is now widely recognized, with Newsweek recently including PROs as a criterion in its global hospital rankings [6]. Notably, research, particularly in oncology, demonstrates that PROs can improve patient survival rates [8].

However, 4 years after COMPASS, similar initiatives remain scarce. Our literature review [9,10] confirms this gap, and a technology search for freely available frameworks similar to COMPASS yielded minimal results [10]. Several factors contribute to this limited adoption [11], including stringent regulatory requirements, high development costs, and the rapid evolution of smartphone technology [12]. Additionally, many apps fail to prioritize user needs, lack comprehensive guidelines, and struggle to integrate into existing health care workflows. The broader digital health sector faces challenges in integrating health apps into clinical practice. While many apps exist, most lack clinical validation and remain underused. Key barriers include education and awareness gaps, missing digital formularies, limited workflow integration, and unclear reimbursement models. The digital divide also persists, preventing some populations from accessing or effectively using these technologies. Furthermore, the impact of health apps on clinician workload and burnout remains insufficiently studied.

A substantial body of literature exists on COVID-19 health apps [13,14]. However, many studies overlook a significant number of available apps [15,16], and those that do include them often fail to address broader mHealth frameworks for pandemic management. There are several initiatives related to COMPASS [17,18], some closely aligned and others more general in scope. However, none provide the comprehensive, interdisciplinary approach that COMPASS offers. Research has consistently highlighted barriers to adoption [19,20], reinforcing the need for fundamental frameworks such as COMPASS in both mHealth apps and PRO integration.

Our objectives were as follows:

The following instruments were used:

The findings showed that no direct equivalent to COMPASS exists internationally at the time of development, highlighting the necessity of a structured, interoperable pandemic app framework. However, several international initiatives and frameworks provide valuable insights and technical solutions (Table 3).

In addition, we identified 14 pandemic-related frameworks, 13 of which focus on contact tracing (Table 4). The most notable ones are described below.

The international survey assessed pandemic app initiatives and COMPASS’s relevance. Key insights:

A governance structure was established to monitor project milestones, enable rapid response to deviations, and ensure alignment with AC2. Effective communication and coordination with international pandemic networks were prioritized to synchronize technical developments.

Best practices and guidelines were developed to enhance the effectiveness, efficiency, and research compatibility of pandemic apps. A digital knowledge database was created to support partners in meeting regulatory requirements. Advisory structures were also established to disseminate these guidelines.

Regulatory demands for pandemic apps proved more stringent than for standard medical apps, requiring a different development approach. Guidelines were formulated to address these challenges and ensure compliance with fast-evolving requirements.

Ethical considerations were critical due to public concerns over mandatory app usage during pandemics. The cluster focused on trust-building measures to help citizens and researchers navigate the ethical implications of pandemic apps.

Key requirements for using app-collected data in pandemic research were identified. Concepts and recommendations were developed to guide app configuration, which were integrated into AC2. A generic HL7 FHIR (Fast Healthcare Interoperability Resources) interface was initially created and iteratively expanded to accommodate specific data models [38].

A modular technology platform was developed, featuring templates, technical components, and a semiautomated compliance check for regulatory adherence. Reference implementations for both native and cross-platform development were provided, all under open-source licenses, ensuring quick adaptability for future pandemics.

Long-term strategies were designed to ensure the ongoing operation of the platform, including regular updates aligned with legal and scientific advancements. A certification framework was proposed, alongside a responsive advisory structure for future pandemics. Maintenance efforts focused on keeping apps compatible with evolving mobile operating systems.

This pillar highlights the successful deployment of multiple study-related apps (Table 5):

This domain primarily focused on the extensive development of the questionnaire editor, with detailed technical specifications available at [39]. Simultaneously, ongoing maintenance and enhancement efforts have ensured the optimization of key components, as outlined in [40].

For example, within the InnovationHub CAEHR project, findings on Medical Device Regulation and eHealth insights have been successfully integrated and reused. Regular high-frequency monthly inquiries about these results ensure their continued relevance and refinement.

The COMPASS initiative demonstrates that effective pandemic mHealth apps require systemic coordination beyond technological innovation. While designed for pandemic response, its framework addresses fundamental challenges in health care digitalization: balancing rapid innovation with regulatory compliance, integrating patient-generated data into research infrastructure, and ensuring interoperability across fragmented systems. The emphasis on PROs and standardized data collection has implications extending to chronic disease management, remote monitoring, and routine clinical care. However, COMPASS’s experience raises critical questions about whether such frameworks can be sustained outside crisis contexts that create urgency and overcome traditional implementation barriers.

Despite COMPASS’s open-source design and adherence to international standards (HL7 FHIR and FAIR [Findable, Accessible, Interoperable, Reusable] principles), its transferability across different contexts remains uncertain. The absence of similar international initiatives suggests deeper structural barriers: fragmented health care systems, varying regulatory environments, and insufficient incentives for collaborative development in health care. Moreover, the framework’s applicability to resource-limited settings or endemic disease management requires further exploration.

User adoption challenges persist beyond technical solutions. Digital health apps inherently exclude populations without devices or digital literacy, potentially exacerbating health disparities during crises. While COMPASS surveys suggest German citizens’ willingness to share health data, this may not generalize globally, and trust deficits reflect broader concerns about data capitalism and surveillance that technical measures like encryption cannot fully address. Future frameworks must explicitly engage with health equity and meaningful public participation in governance.

A notable gap in COMPASS evaluation is a detailed analysis of integration into clinical workflows and impact on health care provider workload. The paper acknowledges that clinician burden remains insufficiently studied, yet this represents a critical implementation challenge for already strained health care systems. While COMPASS’s modular design addresses adaptability, questions remain about long-term maintenance responsibilities, evolution alongside changing technology, and the effectiveness of proposed sustainability structures beyond initial project funding.

Several critical research questions emerge: how do COMPASS apps perform against alternatives in terms of data quality and public health impact? What organizational factors enable successful adoption? How can apps serve diverse populations with varying digital access? What business models support ongoing maintenance beyond project funding? The nearly 1 million data points collected demonstrate feasibility but not effectiveness or translational impact.

COMPASS’s navigation of Medical Device Regulation offers valuable lessons for regulatory frameworks during health emergencies, suggesting the need for expedited pathways that maintain safety standards. The international fragmentation in pandemic app approaches indicates potential value in World Health Organization (WHO)–convened coordination mechanisms, though questions of sovereignty and resource distribution complicate such efforts.

The evaluation focuses on process and outputs rather than health outcomes. Whether COMPASS apps improved pandemic management or public health decision-making remains unclear. The paper predominantly reflects developer and researcher perspectives rather than end users, health care providers, or public health officials—stakeholder voices that should be centered in future work.

The 4-year gap since completion offers an opportunity to assess actual sustainability: which components remain actively maintained? Did proposed advisory structures and certification frameworks materialize? What barriers emerged? These questions are critical for understanding whether COMPASS achieved its objectives and informing future initiatives.

In summary, COMPASS demonstrates that coordinated, interdisciplinary pandemic app development is feasible, but translating technical capabilities into sustained public health impact requires addressing deeper challenges of trust, equity, clinical integration, and institutional sustainability. The true test lies not in what COMPASS achieved during its funding period, but whether its components influence subsequent digital health initiatives and improve preparation for future pandemics. COMPASS should be understood as the beginning of a longer conversation about digital health infrastructure rather than its conclusion.

COMPASS is a cohesive initiative in medical informatics, bringing together interdisciplinary expertise to develop a structured platform for coordinating pandemic apps and technology. It underscores the role of smartphones in health communication and the importance of public trust and adoption for effective pandemic response. By integrating technology into health care, COMPASS provides a practical framework for future medical research and public health strategies, particularly in health crises. Through its collaborative approach, it addresses current challenges while laying the groundwork for future advancements in health care technology and research.