Testing for the presence of the SARS-COV-2 virus will play a pivotal role in the control of the COVID-19 pandemic. There is currently an abundance of assays (i.e. tests) on the market. Many of them are not thoroughly validated or have been provisionally authorised after an emergency validation procedure. In order to limit false-negative and false-positive results, it is important to define common criteria that SARS-COV-2 assays have to fulfil. VALCOR is a project designed by scientists of Sciensano and international virologists. It aims to contribute in setting up a framework for test validation. The result will be the publication of well-validated assays that can be used safely for diagnosis of patients, screening of risk groups or tracing of suspicious contacts.
The aim of VALCOR is to develop a study protocol for comparison and validation of assays that:
- detect presence of SARS-COV-2 virus in patients with COVID-19 disease or
- are used for screening of carriers of SARS-CoV-2 virus.
This by identifying its viral RNA or by identifying viral proteins in oro-pharyngeal, nasopharyngeal human specimens or other specimens from the respiratory tract.
The VALCOR protocol is inspired on VALGENT (VALidation of HPVGENotyping Tests) which is a successful forum for comparison and validation of human papillomavirus tests usable for cervical cancer screening (Ref. 1* & 2**).
Each participating VALCOR reference laboratory will prepare a VALCOR panel consisting of:
- stored human specimens already tested for presence of RNA of SARS-COV-2 and
- standardised artificial specimens provided by the Joint Research Centre of the European Commission containing calibrated amounts of viral RNA.
All samples will be aliquotted and subsequently sent to client laboratories, i.e. manufacturers of SARS-COV-2 assays or laboratories that have developed in house SARS-COV-2 tests. These client laboratories will perform their SARS-COV-2 tests on all aliquots of the VALCOR panel.
The unit Cancer Epidemiology (Cancer Centre) at Sciensano will receive and link both the results of the:
- original testing done in the Corona reference laboratory and
- tests performed at the client laboratories to validate their assay.
The outcomes of VALCOR will be the:
- development of principles of robust SARS-COV-2 test validation
- generation of an international network for SARS-COV-2 test comparison
- publication of a list of assays that can be used safely in the field of COVID-19 control.
1* Arbyn M, et al. VALGENT: a protocol for clinical validation of human papillomavirus assays. J Clin Virol 2016;76 (Suppl 1): S14-S21
2** Bonde J, et al. The Valgent4 protocol: Robust analytical and clinical validation of 11 HPV assays with genotyping on cervical samples collected in SurePath medium. J Clin Virol 2018;108: 64-71.