Results From the Third and Fourth WHO External Quality Assessments for the Molecular Detection of Respiratory Syncytial Virus

Abstract

BACKGROUND: In 2016, the World Health Organization (WHO) initiated the global RSV surveillance programme, which aimed to strengthen laboratory diagnostic capacity and evaluate molecular detection test performance. External quality assessments (EQAs) are conducted regularly as part of this programme to ensure ongoing laboratory proficiency. The third (2021-2022) and the fourth (2023-2024) WHO RSV EQAs were conducted to evaluate the ability of participating laboratories to accurately detect and subtype RSV. METHODS: For each EQA panel, 12 lyophilised RSV isolates were prepared using both recently circulating and RSV strains used in previous EQAs. The isolates were shipped to 81 and 85 laboratories in the third and fourth EQA, respectively. Participants tested the specimens using their routine molecular diagnostic protocols and reported the results through the UK NEQAS online platform. Performance was evaluated based on detection and subtyping accuracy, and a scoring system was used that ranged from good performance (24/24 correct results) to unacceptable (≤ 16 correct results). RESULTS: A total of 73 (90.1%) and 74 (87.1%) laboratories returned results for the third and fourth RSV molecular EQAs, respectively. In the third EQA, 69.9% of laboratories were classified as good, 15.1% as acceptable and 1.4% as satisfactory, resulting in 86.3% within the desirable range; 12.3% were unacceptable and 1.4% poor. In the fourth EQA, 60.8% were good, 28.4% acceptable and 2.7% satisfactory, with 91.9% in the desirable range; 8.1% were unacceptable, and none were poor. CONCLUSION: The third and fourth WHO RSV EQA demonstrated good overall laboratory performance for RSV molecular detection and subtyping. These findings highlight the importance of EQA to document high-quality diagnostics, especially with the introduction of RSV vaccines and monoclonal antibodies. Ongoing EQAs, including the first WHO RSV sequencing EQA initiated in 2024, will further enhance global laboratory capacity for RSV surveillance and outbreak response.