Building Quality Control for Molecular Assays in the Global Measles and Rubella Laboratory Network

Abstract

More than 100 laboratories in the World Health Organization Global Measles and Rubella Laboratory Network (GMRLN) perform nucleic acid-based methods for case confirmation of measles or rubella infections and/or strain surveillance (genotyping). The quality of laboratory data is critical to ensure that diagnostic results and country reports to regional verification committees are based on accurate data. A molecular External Quality Assurance (mEQA) program was initiated by the US-CDC in 2014 to evaluate the performance of laboratories in the network. The inclusion of testing for measles and rubella viruses, with a focus on detection and genotyping, plus the diversity of assays and platforms employed required a flexible and comprehensive proficiency testing program. A stepwise introduction of new evaluation criteria gradually increased the stringency of the proficiency testing program, while giving laboratories time to implement the required changes. The mEQA program plays an important role in many processes in the GMRLN, including informing plans for the training of laboratory staff, access to reagents, and the submission of sequence data to global databases. The EQA program for Local Public Health Institutes in Japan is described as an example for national mEQA programs. As more laboratories initiate molecular testing, the mEQA will need to continue to expand and to adapt to the changing landscape for molecular testing.

Keywords: external quality assessment; genotyping; measles; rubella.

Figure 1

Measles and rubella proficiency panels consist of disks of FTA^® cards loaded with virus lysates. The figure shows a measles proficiency panel from the 2023 round of the mEQA program. (A) Tubes with FTA^® card disks. (B) Box sealed with desiccant to protect from humidity.

Figure 2

Excerpt from the feedback report. Since 2022, evaluation has been divided into three parts: detection, RT-PCR to amplify DNA for sequencing, and genotyping (sequencing and sequence analysis). Laboratories may participate in all or only some parts. Laboratories may pass or fail each part individually; (A). Summary report, (B). Scoring report.

Figure 3

Number of participating laboratories per WHO region from 2014 to 2022. “Failed” depicts the number of laboratories that did not pass a retest. Note: The European Region did not participate in 2015–2017.