Optimised mapping of seroprevalence data according to time, targeted populations and categorised assays

Task 84 Harmonisation of seroprevalence data for COVID19 and generation of a seroprevalence map of EuropeLead AMU other partners involved UCD UKHD EMBLSeroprevalence studies represent a major epidemiological and public health tool They allow evaluating the attack rate in general or specific populations and estimating the immune status and thus the vulnerability to further spread of the outbreak of these populations In particular data from such surveys are needed over time to track the immune status of populations and to determine if and when the prevalence of antibodypositive individuals is reaching a point at which herd immunity can be anticipated Before reaching herd immunity the data can also be used to calibrate mathematical models and inform public health officials about transmission dynamics The methodology of assays has not been harmonised nor completely optimised Different proteins mainly the envelope and the nucleoprotein the latter being more conserved among coronaviruses and different classes of antibodies IgG IgA IgM are targeted by ELISA tests Neutralisation assays unfrequently use the reference PRNT technique which is poorly adapted to large series and cannot be automated When virus neutralisation tests VNT are used in a 96well format the amount of virus varies among investigators most frequently in the range of 50100 TCID50 per assay which produces different neutralising titres In addition different pseudoneutralisation assays have been implemented This is convenient since the assay can be performed outside a BSL3 laboratory However the density of envelope proteins on the surface of pseudoviruses is usually much lower that observed in wildtype virions Consequently low amounts of antibodies can neutralise such pseudoviruses and pseudo neutralisation techniques produce much higher neutralising titres than traditional techniquesOther important sources for heterogeneity between serological surveys are the lack of comparative data between the multitude of both commercial N 230 on the FIND website and inhouse assays and the differences between studies with regard to the design and the choice of the target populations Thus seroprevalence studies may provide a constellation of unrelated pictures in the absence of harmonisation efforts It is unrealistic at this stage to propose a full standardisation of assays Rather what is currently required is i the implementation of a comparator panel that would link the different seroprevalence surveys and would allow proposing a sound dynamic map of seroprevalence across Europe ii an expert analysis of epidemiological and biological study designs to provide skills and scientific content for optimizing data sharing and data comparabilitySpecific subtasks Subtask 841 Situational Analysis to establish in conjunction with the WHO solidarity II serology consortium and from other sources if publicly available a mapping of serosurvey efforts in Europe including the technical details of testing and study designSubtask 842 Toolbox for sound comparison of independently produced seroprevalence data This includes a literature analysis to optimise the characterisation of testing methods ie sensitivity specificity antigens crossreactivity etc reconciling algorithms for heterogenous seroprevalence data and a roadmap for comparative analysisSubtask 843 Networking for implementation of comparator panels for improvement of standardizsation We will contact potential partners Eur Blood alliance Eur Virus Archive WHO using synergies with existing projects see below to promote the implementation of comparator panels to improve the comparability of related assays according to antigen and assay type Synergies The partners are members of the WHO Solidarity II serology consortium which encompasses a large number of ongoing and planned serosurveys in Europe and globallyAt