biostudies-literaturePiano Mortari EItalian Ministry of Health2541https://www.ebi.ac.uk/biostudies/studies/S-EPMC8533837biostudies-literatureUnknown10(10)Specific memory B cells and antibodies are a reliable read-out of vaccine efficacy. We analysed these biomarkers after one and two doses of BNT162b2 vaccine. The second dose significantly increases the level of highly specific memory B cells and antibodies. Two months after the second dose, specific antibody levels decline, but highly specific memory B cells continue to increase, thus predicting a sustained protection from COVID-19. We show that although mucosal IgA is not induced by the vaccination, memory B cells migrate in response to inflammation and secrete IgA at mucosal sites. We show that the first vaccine dose may lead to an insufficient number of highly specific memory B cells and low concentration of serum antibodies, thus leaving vaccinees without the immune robustness needed tCellsHighly Specific Memory B Cells Generation after the 2nd Dose of BNT162b2 Vaccine Compensate for the Decline of Serum Antibodies and Absence of Mucosal IgA.PMC8533837RF2013-02358960 grantCOVID-2020-12371817 grantTerreri SRuggiero AFernandez Salinas AAgosta MRoscilli GMagnavita NRusso NLocatelli FMeschi SCotugno NZaffina SAlteri CPiano Mortari ELinardos GPiccioni LBrugaletta RCarsetti RRusso CSalvatori GGiorgio DColtella LSantoro APavoni ECorsetti TAgrati CVinci MRCastilletti CRanno SCamisa VColagrossi LCiofi Degli Atti MLPerno CFAmodio DAlbano CRomania PfalseHighly Specific Memory B Cells Generation after the 2nd Dose of BNT162b2 Vaccine Compensate for the Decline of Serum Antibodies and Absence of Mucosal IgA.Specific memory B cells and antibodies are a reliable read-out of vaccine efficacy. We analysed these biomarkers after one and two doses of BNT162b2 vaccine. The second dose significantly increases the level of highly specific memory B cells and antibodies. Two months after the second dose, specific antibody levels decline, but highly specific memory B cells continue to increase, thus predicting a sustained protection from COVID-19. We show that although mucosal IgA is not induced by the vaccination, memory B cells migrate in response to inflammation and secrete IgA at mucosal sites. We show that the first vaccine dose may lead to an insufficient number of highly specific memory B cells and low concentration of serum antibodies, thus leaving vaccinees without the immune robustness needed t2021-01-01T00:00:00Z2021 Sep2025-04-20T02:03:24.318Z2025-04-20T02:03:24.318ZS-EPMC85338373468552110.3390/cells10102541