A-292 The Use of Third-Party Controls During Covid-19 Pandemic: An Alternative to the Lack of Other Respiratory Infections
Authors: Sánchez-Sánchez J 
Published: September 2023

Abstract

Background
Since SARS-CoV-2 spread widely around the world, previously well-established infectious patterns have changed. The introduction of a new respiratory pathogen, together with changes in human behaviour, such as restrictions on social interactions and the use of facemasks, led to a decrease in the circulation of influenza and respiratory syncytial viruses. This phenomenon, together with the collapse of the healthcare system, significantly decreased the availability of certain types of samples for use in clinical studies to evaluate the performance of in vitro diagnostic products. To overcome this issue, EQA programmes are an excellent alternative. This material has been designed to be used in any equipment, kit or following any specific protocol, as the aim is to mimic human specimens. Thus, the CE-IVD Vitassay qPCR FluA + FluB + RSV, an assay for the detection and differentiation of Flu A, Flu B and RSV, has been routinely tested with material from QCMD programmes containing different strains and serotypes of Influenza and RSV.

Methods
Vitassay qPCR FluA + FluB + RSV (Vitassay Healthcare SLU, Huesca, Spain) is a commercial kit consisting in a ready-to-use lyophilized master mix. This kit has been blindly tested with controls from 4 QCMD panels including RSV, influenza A and B (2020–2022). Each panel consist of 10 specimens in transport media, which were handled following the programme indications. RNA was extracted using automatic extraction (MagDEA Dx SV kit on the 12gC or Vitassay Microorganism-NA Isolation kit on the KingFisher Flex Automatic platform). Amplification was performed on BioRad systems (CFX96 and CFX96 OPUS). Interpretation of the results was done following manufacturer’s instructions. Sensitivity, specificity, and Likelihood Ratio have been calculated with a 95% confidence interval using the software MetaDiSC 1.4.

Results
In total, 40 human-like samples from QCMD EQA programmes were analysed with Vitassay qPCR Flu A + Flu B + RSV during Covid-19 Pandemic. Vitassay reported 14 Influenza A positive samples, 11 influenza B and 12 RSV positive samples; all of them were correctly detected when compared the initial characterisation. For Flu A sensitivity and specificity were of 1 (0,76–1) and 1 (0.86–1), LR+ 52.2 (3.34–814.62), LR− 0.034 (0.002–0.51). For Flu B sensitivity and specificity were of 1 (0.71–1) and 1 (0.88–1), LR+ 57.5 (3.67–900.49), LR− 0.042 (0.003–0.63). For RSV sensitivity and specificity were of 1 (0,73–1) and 1 (0.87–1), LR+ 55.76 (3.56–872.35), LR− 0.039 (0.003–0.59).

Conclusions
Third party controls are an excellent alternative to clinical samples, especially in extraordinary circumstances. In addition, they allow to introduce different strains and variants, such as the QCMD specimens tested. Among these, we could find a such as H1N1 and H3N2 Influenza A serotypes, Influenza B Yamagata and Victoria and RSV A and B, which were properly detected by Vitassay multiplex. In addition, Vitassay extraction kit showed satisfactory results as all samples were properly detected when used in combination with Vitassay qPCR Flu A + Flu B + RSV.