Assessment of High-Titer Convalescent Plasma as an Adjunctive Therapy in the Reduction of Mortality Rate and Viral Load in Patients with Severe COVID-19: A Meta-Analysis

COVID-19 has emerged as the "first pandemic of the 21st Century" and continues to pose challenges to global health. Currently, the most common symptomatic management of COVID-19 patients involves isolation and oxygen therapy. However, present protocols are still deemed insufficient; hence, other treatment options are being considered and tested. This includes convalescent plasma therapy (CPT), which involves a strategy of passive immunization. With this, the primary objective of this systematic review/meta-analysis is to collate, systematically compare, and synthesize available clinical trials involving convalescent plasma (CP), more specifically, high-titer CP, as adjunctive therapy in the treatment of patients with severe COVID-19. This was accomplished by comparing the effect of high-titer CP with standard treatment alone, in terms of mortality rate and viral clearance, by reviewing selected studies based on an inclusion-exclusion criteria and synthesizing selected studies through qualitative analysis and meta-analysis. A total of five studies were included, which consist of: three randomized clinical trials (RCTs); one retrospective trial; and one single arm trial. Four studies were subjected to meta-analysis for mortality rate. For instance, it was determined that the overall incidence mortality rate of patients who received high-titer CP is 11.59% of the experimental group, while the incidence mortality rate of patients who only received standard care is 20.25% of the control group (Risk Ratio (RR), 0.71; 95% confidence interval (CI),0.46-1.09; P-value = 0.46). Moreover, three of the included trials were subjected to qualitative analysis, all of which depicted undetectable viral levels in some patients as early as 3 days, while others exhibited a steady decline. Treatment of COVID-19 with the use of high-titer convalescent plasma as an adjunctive therapy, compared with standard care or treatment, was not significantly associated with reduction of all-cause mortality. High-Titer CPT also shows potential in increasing COVID-19 viral clearance, which indicates an antiviral effect; however, controlled clinical trials with comparator or placebo groups are needed to further support these findings.