Sigal GB, Novak T, Mathew A, Chou J, Zhang Y, Manjula N, Bathala P, Joe J, Padmanabhan N, Romero D, Allegri-Machado G, Joerger J, Loftis LL, Schwartz SP, Walker TC, Fitzgerald JC, Tarquinio KM, Zinter MS, Schuster JE, Halasa NB, Cullimore ML, Maddux AB, Staat MA, Irby K, Flori HR, Coates BM, Crandall H, Gertz SJ, Randolph AG, Pollock NR. Measurement of SARS-CoV-2 antigens in plasma of pediatric patients with acute COVID-19 or MIS-C using an ultrasensitive and quantitative immunoassay. medRxiv. 2021 Dec 09.