Back to school: use of Dried Blood Spot for the detection of SARS-CoV-2-specific immunoglobulin G (IgG) among schoolchildren in Milan, Italy.

Abstract Serological surveillance is necessary to the reestablishment of school activities in safe conditions and to avoid school-related outbreaks. In this study, DBS (Dried Blood Spots) have proven to be a simple, rapid and reliable sample collection tool for detecting antibodies against SARS-CoV-2 by ELISA test compared to matched serum samples from venous sampling (R2=0.9553; Pearson's coefficient=0.98; Cohen's unweighted k=0.93; overall agreement=96.2%). This approach may facilitate sample collection from schoolchildren for serological surveys useful to an adequate risk-assessment.