The Logic and History of Passive Immunity and Antibody Therapies

This volume takes a broad overview of antibody-based therapies prior to and during the COVID pandemic and examines their potential use in future pandemics. Passive antibody therapy was the first effective antimicrobial treatment and its development in the early twentieth century helped catalyze immunological and microbiological research. During the era of serum therapy (1890-1940) antibody-based therapies were developed against both viral and bacterial diseases. Effective treatment required an understanding of how to quantify antibodies, how to develop serotype-specific sera and recognition of the need to treat early in disease. Thus, although the era of serum therapy essentially ended with the development of small molecule antimicrobial therapy in the 1940s, antibody-based therapies led to important new scientific understanding, while remaining in use for some toxin and venom-caused diseases and in the prevention of outbreaks of viral hepatitis. A renewed interest in antibody-based therapies was seen in the widespread deployment of convalescent plasma and monoclonal antibodies during the COVID-19 pandemic. Convalescent plasma will likely be the first specific therapy during outbreaks with new pathogens for which there is no other therapy. For all forms of antibody-based therapies, effectiveness relies on the key principles of antibody therapy, namely, treatment early in disease with preparations containing sufficient antibody specific to the microbe in question.

Convalescent serum-derived exosomes: Attractive niche as COVID-19 diagnostic tool and vehicle for mRNA delivery

The spread of SARS-CoV-2 over the entire world is more commonly known as COVID-19. COVID-19 has impacted society in every aspect of routine life. SARS-CoV-2 infection is often misdiagnosed as influenza or seasonal upper respiratory tract viral infections. General diagnostic tools can detect the viral antigen or isotypes of antibodies. However, inter- and intraindividual variations in antibody levels can cause false negatives in antibody immunoassays. On the contrary, the false-positive test results can also occur due to either cross-reactivity of the viral antigens or some other patient-related autoimmune factors. There is need for a cogent diagnostic tool with more specificity, selectivity, and reliability. Here, we have described the potential of convalescent serum-derived exosome as a diagnostic tool for the detection of SARS-CoV-2, even in asymptomatic patients, which is a limitation for currently practiced diagnostic tests throughout the globe. In addition, its potential as a vehicle for messenger RNA (mRNA) delivery is also emphasized.

Differences in Inflammation, Treatment, and Outcomes Between Black and Non-Black Patients Hospitalized for COVID-19: A Prospective Cohort Study

PURPOSE

Racial disparities in coronavirus disease 2019 (COVID-19) outcomes have been described. We sought to determine whether differences in inflammatory markers, use of COVID-19 therapies, enrollment in clinical trials, and in-hospital outcomes contribute to racial disparities between Black and non-Black patients hospitalized for COVID-19.

METHODS

We leveraged a prospective cohort study that enrolled 1325 consecutive patients hospitalized for COVID-19, of whom 341 (25.7%) were Black. We measured biomarkers of inflammation and collected data on the use COVID-19-directed therapies, enrollment in COVID-19 clinical trials, mortality, need for renal replacement therapy, and need for mechanical ventilation.

RESULTS

Compared to non-Black patients, Black patients had a higher prevalence of COVID-19 risk factors including obesity, hypertension, and diabetes mellitus and were more likely to require renal replacement therapy (15.8% vs 7.1%, P < .001) and mechanical ventilation (37.2% vs 26.6%, P < .001) during their hospitalization. Mortality was similar between both groups (15.5% for Blacks vs 14.0% for non-Blacks, P = .49). Black patients were less likely to receive corticosteroids (44.9% vs 63.8%, P< .001) or remdesivir (23.8% vs 57.8%, P < .001) and were less likely to be enrolled in COVID-19 clinical trials (15.3% vs 28.2%, P < .001). In adjusted analyses, Black race was associated with lower levels of C-reactive protein and soluble urokinase receptor and higher odds of death, mechanical ventilation, and renal replacement therapy. Differences in outcomes were not significant after adjusting for use of remdesivir and corticosteroids.

CONCLUSIONS

Racial differences in outcomes of patients with COVID-19 may be related to differences in inflammatory response and differential use of therapies.

Review of Current Advances in Serologic Testing for COVID-19

OBJECTIVES

To examine and summarize the current literature on serologic methods for the detection of antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

METHODS

A literature review was performed using searches in databases including PubMed, medRxiv, and bioRxiv. Thirty-two peer-reviewed papers and 23 preprints were examined.

RESULTS

The studies included lateral flow immunoassay, enzyme-linked immunosorbent assay, chemiluminescence immunoassay, and neutralizing antibody assays. The use of all major SARS-CoV-2 antigens was demonstrated to have diagnostic value. Assays measuring total antibody reactivity had the highest sensitivity. In addition, all the methods provided opportunities to characterize the humoral immune response by isotype. The combined use of IgM and IgG detection resulted in a higher sensitivity than that observed when detecting either isotype alone. Although IgA was rarely studied, it was also demonstrated to be a sensitive marker of infection, and levels correlated with disease severity and neutralizing activity.

CONCLUSIONS

The use of serologic testing, in conjunction with reverse transcription polymerase chain reaction testing, was demonstrated to significantly increase the sensitivity of detection of patients infected with SARS-CoV-2. There was conflicting evidence regarding whether antibody titers correlated with clinical severity. However, preliminary investigations indicated some immunoassays may be a surrogate for the prediction of neutralizing antibody titers and the selection of recovered patients for convalescent serum donation.