Benchmarks for protective immunity from infection or severe disease after SARS-CoV-2 vaccination are still being defined. Here we characterized virus neutralizing and ELISA antibody levels, cellular immune responses, and viral variants in 4 separate groups: Healthy control participants weeks (early) or months (late) following vaccination in comparison to symptomatic SARS-CoV-2 infections after partial or full mRNA vaccination. During the study time, most symptomatic breakthrough infections were caused by the SARS-CoV-2 Alpha variant. Neutralizing antibody levels in the healthy controls were sustained over time against the vaccine parent virus, but decreased against the Alpha variant, whereas IgG titers and T cell responses against the parent virus and Alpha variant declined over time in healthy controls. Both partially and fully vaccinated patients with symptomatic infections had lower virus neutralizing antibody levels against parent virus than the healthy controls, similar IgG antibody titers and similar virus-specific T cell responses measured by IFN-g. Compared to healthy controls, neutralization activity against the Alpha variant was lower in the partially vaccinated infected patients and tended toward lower in the fully vaccinated infected patients. In this cohort of breakthrough infections, parent virus neutralization was the superior predictor of breakthrough infections with the Alpha variant of SARS-CoV-2. Summary: Despite similar antibody titers and T-cell responses to vaccinated noninfected healthy controls, neutralizing capacity was reduced in those with breakthrough infection.

In this manuscript, we employ parallel batch stability and chromatographic screens in concert with linear and step gradient experiments to develop a high yield, HCP clearance anion exchange capture process for lentiviral vector (LVV) purification. An initial broad resin screen is carried out to determine anion exchange‐based resins that exhibit high recovery of LVV. LVV stability is then evaluated and conditions are established where the vector exhibits good stability, namely phosphate buffer at pH 6.5–7.5, with low to moderate salt concentrations. A subsequent high‐throughput batch screen is then carried out with a subset of resins selected from the first screen under stable conditions to identify optimal wash and elution steps to further improve product yield and protein clearance. Linear gradient experiments are also conducted in mini‐column format to refine the operating conditions and final step gradient processes are established that exhibit greater than 70% yield of infectious LVV while also achieving up to 2.89 log reduction values (LRV) of HCPs during the process. The large set of stability and chromatographic data provided in this work represent an important contribution to knowledge in the field about the chromatographic efficacy of a wide range of resins for LVV bioprocessing under stable conditions.

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