Overview: A comprehensive post-pandemic evaluation
This study presents a cross-sectional evaluation of the Philippines’ surveillance systems for COVID-19 and other respiratory viruses as of April 2023. Conducted across national, regional, and local levels, the mixed-methods assessment examined operations, interconnectivity, and performance to identify opportunities for sustainable, multisource respiratory virus surveillance. The project centered on six systems: COVID-19 case-based surveillance, traveler screening, SARS-CoV-2 genomic surveillance, Influenza-Like Illness (ILI) surveillance, Severe Acute Respiratory Infection (SARI) surveillance, and an RSV sentinel pilot.
Approach and key objectives
Researchers used three linked data streams to answer core questions: (1) describe structure and processes across administrative levels, (2) assess user-centric attributes such as usefulness, acceptability, and flexibility, (3) evaluate performance indicators like completeness, representativeness, timeliness, and overall quality, and (4) determine how surveillance data describe person, place, and time of respiratory virus transmission. Data collection spanned four weeks in April 2023, with 26 site visits across national, regional, and local health offices and hospitals.
What systems were evaluated and where
Evaluated systems included universal COVID-19 case reporting, traveler screening, genomic sequencing, and sentinel networks for ILI, SARI, and RSV. Evaluation sites covered three regions (Cordillera Administrative Region, Eastern Visayas, and the National Capital Region), illustrating urban, island, and mountainous contexts with varying capacity. This landscape highlighted how surveillance is deployed in diverse settings and where interoperability gaps hinder rapid public health action.
Findings: performance, data flow, and capacity
Surveillance scope and design
The DOH expanded surveillance during the pandemic by creating new databases and information systems, such as COVIDKaya, TKC, CDRS, and updated notifiable disease systems (PIDSR-IS and EDCS-IS). While this created a robust data backbone for COVID-19 and ILI/SARI, fragmentation emerged as multiple, not fully interoperable systems operated concurrently. Staff reported using ad hoc tools (Google Sheets, Excel, messaging apps) due to interoperability challenges and inconsistent access to historic data.
System performance and data quality
Completeness of critical variables varied by system. Demographic data such as sex and residence were generally complete, but other variables like patient outcomes were missing in some networks (SARI) or less consistently captured (COVID-19 case-based surveillance). Timeliness varied significantly: COVID-19 case-based surveillance delivered results quickly (median 3 days from symptom onset to lab reporting), while sentinel systems showed longer lags (ILI: ~14 days, SARI: ~20 days, RSV: ~19 days). This reflects the urgency of pandemic reporting versus routine surveillance needs.
Geographic coverage and representativeness
Regional differences in coverage and reporting hinder direct comparability. High case rates in COVID-19 did not always align with high ILI or SARI counts, underscoring how sentinel site distribution and surveillance intensity shape apparent burden. The evaluation emphasized caution when interpreting incidence without standardized catchment areas.
Laboratory capacity and genomics
Testing expanded rapidly, with SARS-CoV-2 molecular testing increasingly centralized in accredited laboratories and sequencing capacity expanding nationally. Turnaround for lineage assignment averaged two weeks, and cumulative sequencing data fed into global platforms. However, there were constraints: limited bioinformatics support and a lack of in-country multiplex testing for non-SARS-CoV-2 pathogens, highlighting gaps in comprehensive respiratory-virus genomics.
Recommendations for right-sizing and integration
The evaluation proposes a two-phased approach: (1) right-size universal COVID-19 surveillance by scaling back universal case reporting, strengthening sentinel networks, and integrating systems; (2) plan for integrating influenza, SARS-CoV-2, and RSV into a single, cohesive surveillance model. Key actions include transitioning from daily to weekly/bi-weekly reporting, re-evaluating antigen testing where molecular capacity is available, and maintaining regular sequencing uploads to GISAID for variant tracking.
Strategic emphasis is placed on: (a) sustaining sentinel surveillance as the primary backbone for integrated respiratory surveillance, (b) improving interoperability and standardization across reporting tools, (c) clarifying roles and responsibilities to reduce data silos, and (d) investing in workforce sustainability through training and stable contracts. The Mosaic Respiratory Surveillance Framework and WHO guidance on integrating surveillance across influenza, SARS-CoV-2, and RSV underpin these recommendations, aiming for a harmonized, multi-source system with improved data quality and actionable insights.
Limitations and global context
Limitations include non-national representativeness, fragmented sub-national data, and evolving systems since 2023. Nonetheless, the Philippines’ experience mirrors global trends: rapid system expansion during crises, ongoing interoperability challenges, and the need to transition from emergency to sustainable, integrated surveillance.
Looking ahead
Moving toward an integrated, interoperable viral respiratory surveillance system aligns with international best practices. By harmonizing data elements, streamlining reporting channels, and investing in resilient laboratory and human-resource capacity, the Philippines can sustain robust surveillance that informs timely public health action well beyond the pandemic era.
