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. 2023 May 12. Online ahead of print. doi: 10.1016/j.jaip.2023.05.005

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Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.

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Products analyzed by expiration year for IgG binding activities against (A) recombinant SARS-CoV-2 RBD, (B) spike, and (C) NP using ELISA. Graph represents the number of samples testing positive and negative for binding to SARS-CoV-2 proteins. A clear upward trend emerges, with approximately 60% and 85% of the Ig products with expiration dates of 2023 and 2024 testing positive for binding to SARS-CoV-2 proteins, respectively.