Faster decay of neutralizing antibodies in never infected than previously infected healthcare workers three months after the second BNT162b2 mRNA COVID-19 vaccine dose oleh Ilaria Vicenti, Monica Basso, Francesca Gatti, Renzo Scaggiante, Adele Boccuto, Daniela Zago, Eliana Modolo, Filippo Dragoni, Saverio Giuseppe Parisi, Maurizio Zazzi