The Relationship Between SARS-CoV-2 Neutralizing Antibody Titers and Avidity in Plasma Collected From Convalescent Nonvaccinated and Vaccinated Blood Donors

Individual patient and donor seroprofiles in convalescent plasma treatment of COVID-19 in REMAP-CAP clinical trial

OBJECTIVES

Convalescent plasma (CP) treatment of COVID-19 has shown significant therapeutic effect only when administered early. We investigated the importance of patient and CP seroprofiles on treatment outcome in REMAP-CAP CP trial.

METHODS

We evaluated neutralising antibodies (nAb), anti-spike (S) IgM, IgG, IgG avidity, IgG fucosylation and respiratory viral loads in a sub-set of patients (n=80) and controls (n=51) before and after transfusion, comparing them to those in the CP units (n=157) they received.

RESULTS

Most patients were SARS-CoV-2 seropositive pre-transfusion (72% nAb; 89% S-IgG seropositivity). The majority (80%) had higher pre-transfusion S-IgG levels (median 1.7×106 arbitrary units (AU); 56%) or S-IgG production rates (median 1.1×106 AU/day; 64%) than they received from CP (median 2.2×105 AU). Only 22% of the patients demonstrated significant (median 24-fold) increase in their S-IgG levels acquired from transfusion. Better outcomes, measured by organ support-free days, were associated with increase in S-IgM levels (p=0.007), decreased S-IgG fucosylation (p<0.001), lower patient age (p<0.001) but not with receiving CP (p=0.337).

CONCLUSIONS

Based on our data, increased S-antibody levels linked to transfused CP were only observed in pre-seroconversion or immunodeficient patients lacking their own SARS-CoV-2 antibodies, representing the groups where CP treatment has previously shown most benefit.

The role of convalescent plasma and hyperimmune immunoglobulins in the COVID-19 pandemic, including implications for future preparedness

Introduction

When Coronavirus Disease-19 (COVID-19) struck the world in December 2019, initiatives started to investigate the efficacy of convalescent plasma, a readily available source of passive antibodies, collected from recovered patients as a therapeutic option. This was based on historical observational data from previous virus outbreaks.

Methods

A scoping review was conducted on the efficacy and safety of convalescent plasma and hyperimmune immunoglobulins for COVID-19 treatment. This review included the latest Cochrane systematic review update on 30-day mortality and safety. We also covered use in pediatric and immunocompromised patients, as well as the logistic challenges faced in donor recruitment and plasma collection in general. Challenges for low resource countries were specifically highlighted.

Results

A major challenge is the high donation frequency required from first-time donors to ensure a safe product, which minimizes the risk of transfusion-transmitted infectious. This is particularly difficult in low- and middle- income countries due to inadequate infrastructure and insufficient blood product supplies. High-certainty evidence indicates that convalescent plasma does not reduce mortality or significantly improve clinical outcomes in patients with moderate to severe COVID-19 infection. However, CCP may provide a viable treatment for patients unable to mount an endogenous immune response to SARS-CoV-2, based on mostly observational studies and subgroup data of published and ongoing randomized trials. Convalescent plasma has been shown to be safe in adults and children with COVID-19 infection. However, the efficacy in pediatric patients remains unclear.

Discussion

Data on efficacy and safety of CCP are still underway in ongoing (randomized) studies and by reporting the challenges, limitations and successes encountered to-date, research gaps were identified to be addressed for the future.

Conclusion

This experience serves as a valuable example for future pandemic preparedness, particularly when therapeutic options are limited, and vaccines are either being developed or ineffective due to underlying immunosuppression.

Clinical efficacy of SARS-CoV-2 Omicron-neutralizing antibodies in immunoglobulin preparations for the treatment of agammaglobulinemia in patients with primary antibody deficiency

Immunocompromised individuals are at significantly elevated risk for severe courses of coronavirus disease 2019 (COVID-19). In addition to vaccination, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neutralizing antibodies (nAbs) have been applied throughout the pandemic, with time of treatment onset and potency against the currently prevailing virus variant identified as relevant factors for medical benefit. Using data from the European Society for Immunodeficiencies (ESID) registry, the present study evaluated COVID-19 cases in three groups of patients with inborn errors of immunity (IEI; 981 agammaglobulinemia patients on immunoglobulin replacement therapy (IGRT); 8960 non-agammaglobulinemia patients on IGRT; 14 428 patients without IGRT), and the neutralizing capacity of 1100 immunoglobulin lots against SARS-CoV-2 ("Wuhan" and Omicron strains), throughout 3 years. From the first (2020/2021) to the second (2021/2022) cold season, i.e., during the virus drift to the more contagious Omicron variants, an increase in case numbers was recorded that was comparable (~2- to 3-fold) for all three study groups. During the same period, immunoglobulin lots showed a profound nAb increase against the archetypal SARS-CoV-2 strain, yet only low levels of Omicron nAbs. Notably, shortly before the third (2022/2023) cold season, Omicron-neutralizing capacity of released immunoglobulin lots had plateaued at high levels. From the second to the third cold season, COVID-19 cases dropped markedly. While a ~6-fold case reduction was recorded for the groups of non-agammaglobulinemia patients on IGRT and IEI patients not receiving IGRT, the decline was ~30-fold for the group of agammaglobulinemia patients on IGRT. These findings suggest a substantial COVID-19-protective effect of IGRT, at least for distinct groups of antibody-deficient patients.