BackgroundCOVID-19 convalescent plasma (CCP) was widely used as passive immunotherapy during the first waves of SARS-CoV-2 infection in the US. However, based on observational studies and randomized controlled trials, beneficial effects of CCP were limited, and its use was virtually discontinued early in 2021, in concurrence with increased vaccination rates and availability of monoclonal antibody (mAb) therapeutics. However, as new variants of the SARS-CoV-2 spread, interest in CCP derived from vaccine-boosted CCP donors is resurging. The effect of vaccination of previously infected CCP donors on antibodies against rapidly spreading variants of concern (VOC) is still under investigation.Study Design/MethodsIn this study, paired samples from 11 CCP donors collected before and after vaccination were tested to measure binding antibodies levels and neutralization activity against the ancestral and SARS-CoV-2 variants (Wuhan-Hu-1, B.1.1.7, B.1.351, P.1, D614G, B.1.617.2, B.1.427) on the Ortho Vitros Spike Total Ig and IgG assays, the MSD V-PLEX SARS-CoV-2 Panel 6 arrays for IgG binding and ACE2 inhibition, and variant-specific Spike Reporter Viral Particle Neutralization (RVPN) assays.Results/FindingsBinding and neutralizing antibodies were significantly boosted by vaccination, with several logs higher neutralization for all the variants tested post-vaccination compared to the pre-vaccination samples, with no difference found among the individual variants.DiscussionVaccination of previously infected individuals boosts antibodies including neutralizing activity against all SARS-CoV-2 VOC, including the current spreading delta (B.1.617.2) variant. Animal model and human studies to assess clinical efficacy of vaccine boosted CCP are warranted, especially since 15-20% of current donations in the US are from previously infected vaccine-boosted donors.

Background COVID‐19 convalescent plasma (CCP) was widely used as passive immunotherapy during the first waves of SARS‐CoV‐2 infection in the US. However, based on observational studies and randomized controlled trials, the beneficial effects of CCP were limited, and its use was virtually discontinued early in 2021, in concurrence with increased vaccination rates and availability of monoclonal antibody (mAb) therapeutics. Yet, as new variants of the SARS‐CoV‐2 spread, interest in CCP derived from vaccine‐boosted CCP donors is resurging. The effect of vaccination of previously infected CCP donors on antibodies against rapidly spreading variants is still under investigation. Study design/methods In this study, paired‐samples from 11 CCP donors collected before and after vaccination was tested to measure binding antibody levels and neutralization activity against the ancestral Wuhan‐Hu‐1 and SARS‐CoV‐2 variants (Wuhan‐Hu‐1 with D614G, alpha, beta, gamma, delta, epsilon) on the Ortho Vitros Spike Total Ig and IgG assays, the MSD V‐PLEX SARS‐CoV‐2 arrays for IgG binding and ACE2 inhibition, and variant‐specific Spike Reporter Viral Particle Neutralization (RVPN) assays. Results/findings Binding and neutralizing antibodies were significantly boosted by vaccination, with several logs higher neutralization for all the variants tested post‐vaccination compared to the pre‐vaccination samples, with no difference found among the individual variants. Discussion Vaccination of previously infected individuals boosts antibodies including neutralizing activity against all SARS‐CoV‐2 variants.

Implementation of stabilized dried tube specimens (DTSs) for quality control and training would facilitate HIV recency programs, especially in point-of-care settings without cold chain availability. This study shows that addition of the disaccharide trehalose to DTSs prior to drying the samples increased stability of the samples across a range of temperatures.