The paper describes the options available in terms of testing strategies, sample handling and isolation, characterization techniques, method standardization, and outcome reporting. It also describes the laboratory support and exchange of information that ECDC and the WHO Regional Office for Europe can provide to countries in the European region.
Antigenic characterization of SARS-CoV-2 variants analyzes the properties of one virus to help assess how it is related to another virus. This is essential to evaluate the efficacy and immunogenicity of the vaccine, to select the appropriate virus strains for vaccine development, as well as to monitor resistance to antiviral treatments. The antigenic properties of SARS-CoV-2 variants can be characterized by techniques such as plaque reduction neutralization, microneutralization, and pseudovirus neutralization assay.
Rapid exchange of clinical and / or isolated samples of viruses and antigenic data is crucial when a variant with potentially new antigenic properties emerges. In such cases, antigenic data should be shared immediately with the ECDC, the WHO Regional Office for Europe and European surveillance networks. Sending copies to reference laboratories can be supported through the WHO submission mechanism.