biostudies-literatureHarvala HHealth Services and Delivery Research ProgrammeNHS Blood and TransplantNational Institute for Health Research (NIHR)European Commission1347-1354https://www.ebi.ac.uk/biostudies/studies/S-EPMC9348319biostudies-literatureUnknown62(7)<h4>Background</h4>The therapeutic benefit of convalescent plasma (CP) therapy to treat COVID-19 may derive from neutralizing antibodies (nAbs) to SARS-CoV-2. To investigate the effects of antigenic variation on neutralization potency of CP, we compared nAb titers against prototype and recently emerging strains of SARS-CoV-2, including Delta and Omicron, in CP donors previously infected with SARS-CoV-2 before and after immunization.<h4>Methods and materials</h4>Samples were assayed from previously SARS-CoV-2 infected donors before (n = 17) and after one (n = 43) or two (n = 71) doses of Astra-Zeneca or Pfizer vaccinations. Ab titers against Wuhan/wild type (WT), Alpha, Beta, and Delta SARS-CoV-2 strains were determined by live virus microneutralization assay while titers to Omicron used a TransfusionConvalescent plasma donors show enhanced cross-reactive neutralizing antibody response to antigenic variants of SARS-CoV-2 following immunization.PMC9348319101015756RECPLASMora AWebster MCarroll MOtter AClarkson AHopkins VRoberts DJGriffiths ANguyen DLamikanra AALaidlaw SMMaes PKaloyirou FSimmonds PEstcourt LMacLennan SHarvala HTsang HPfalseConvalescent plasma donors show enhanced cross-reactive neutralizing antibody response to antigenic variants of SARS-CoV-2 following immunization.<h4>Background</h4>The therapeutic benefit of convalescent plasma (CP) therapy to treat COVID-19 may derive from neutralizing antibodies (nAbs) to SARS-CoV-2. To investigate the effects of antigenic variation on neutralization potency of CP, we compared nAb titers against prototype and recently emerging strains of SARS-CoV-2, including Delta and Omicron, in CP donors previously infected with SARS-CoV-2 before and after immunization.<h4>Methods and materials</h4>Samples were assayed from previously SARS-CoV-2 infected donors before (n = 17) and after one (n = 43) or two (n = 71) doses of Astra-Zeneca or Pfizer vaccinations. Ab titers against Wuhan/wild type (WT), Alpha, Beta, and Delta SARS-CoV-2 strains were determined by live virus microneutralization assay while titers to Omicron used a 2022-01-01T00:00:00Z2022 Jul2025-04-18T18:07:16.924Z2025-04-07T05:45:32.196ZS-EPMC93483193558831410.1111/trf.16934