Hyperimmune Globulins in COVID-19

The COVID-19 pandemic, resulting from the emergence of the novel coronavirus SARS-CoV-2, posed unprecedented challenges to global health systems as no proven therapy was available. Initially, COVID-19 convalescent plasma (CCP) from recovered COVID-19 patients showed promise as a therapeutic option. However, the efficacy of this approach was closely correlated with the neutralizing antibody titer in the administered plasma and thus effectiveness was not always guaranteed. In response, hyperimmune immunoglobulins (hIG) derived from CCP obtained by apheresis from recovered or vaccinated individuals emerged as a potential alternative. hIG were purified through stringent chromatographic processing from CCP units and displayed varying results in clinical trials, although it seems likely that they improved outcomes compared to placebo or CCP at day 28, particularly in unvaccinated patients. The variability in the effect of hIG likely stems from factors such as the timing of outcome assessment, the administered dose of hIG, the patients' immunological background, and the matching between the variant infecting patients and the neutralization ability of the immunoglobulin batch, which depended on the timing of the CCP collection. Despite logistical challenges and high production costs, hIG showcase advantages over CCP, offering versatility in administration routes and eliminating the need for blood matching, thus facilitating administration in the community, and allowing for variant-specific preparations. hIG appear to be of particular importance in the treatment of immunocompromised patients and patients with persistent COVID-19, although studies in these populations are lacking. Non-human alternatives, such as equine-derived hIG and recombinant hIG, may provide a solution to the logistical challenges of large-scale hIG preparation. Further study is needed to explore these avenues. Establishing the infrastructure for large-scale hIG production independent of plasma donations emerges as a strategic approach for future pandemics, justifying exploration and promotion by health authorities.