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. 2021 Aug 18;59(9):e00559-21. doi: 10.1128/JCM.00559-21

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Copyright © 2021 Ast et al.

This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.

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FIG 2 — EQA design and scope. The flow diagram displays the EQA design and scope. A total of 284 laboratories returned a total of 3,733 results from testing of the 12 different EQA samples provided in three distribution rounds (EQA 1, EQA 2, and EQA 3) of the EQA scheme for anti-SARS-CoV-2 antibody detection. The laboratories could choose to participate in anti-SARS-CoV-2 IgG and/or IgM or IgA detection. The number of participating laboratories, the number of results reported, and the number of different immunoassays used by the participating laboratories are displayed for all three analytes.