Poster Although at the time of this writing its efficacy is uncertain, there are encouraging signs that it reduces mortality and hastens recovery in certain groups of patients, notably those who are treated early in disease and not requiring mechanical ventilation. The rationale for the use of convalescent plasma for COVID is that it will have a therapeutic effect by providing affected individuals with specific antibodies from a host who has recovered.This strategy has a long history of success for other respiratory viral diseases. The observation that patients may not mount measurable antibody responses before day of illness, which then peak around day, suggests that convalescent plasma may be most beneficial early in the course of COVID, before an endogenous antibody response develops. Historically, convalescent plasma was used to treat a range of different illnesses from bacterial meningitis to the influenza pandemic and HN, as well as SARS in. Plasma was most effective when given early in these illnesses.In the preantibiotic era, the time of the appearance of specific antibody in pneumococcal pneumonia was used to support the administration of serum therapy early in the course of disease. This was based on the correlation between the appearance of specific serum antibody and clinical improvement in patients who recovered.Antibodies may mediate antiviral effects through numerous mechanisms including direct antimicrobial effects such as viral neutralization as well as antibodydependent cellular cytotoxicity. In fact, convalescent plasma therapy in patients with COVID, including those with severe disease was shown to mediate viral clearance in several case studies and a randomized controlled trial in which it led to rapid viral clearance from infected tissues. The observation that patients with more severe COVID disease produced higher antibody titers is consistent with what is described in other diseases such as tuberculosis, where more symptomatic patients have higher titer responses. Although some may question the functional significance of high antibody levels in individuals with severe disease and this may raise the concern of detrimental antibody effects, such as antibody dependent enhancement, we caution against such interpretations.Instead, the generation of more antibody is likely to reflect the strong inflammatory response associated with severe disease that contributes to the pathogenesis of COVID. In addition, as patients with severe disease had a higher and more persistent tissue viral burden, stronger antibody responses may correlate with the viral burden.Although this question cannot be answered without clinical trials, it is possible that even patients with late disease may benefit from convalescent plasma if the quality of antibody responses during active disease and convalescence differ.We know that it takes time for antibodies to affinity mature, a process that is likely to imbue them with more effective antiviral properties.Convalescent plasma promotes viral clearance, even in <a href="http://www.targetmol.com/compound/Ibudilast">buy
Ibudilast</a> severely ill patients, even when given more than two weeks after COVID onset study suggests endogenous antibody responses are present.This late viral clearance hints that early and convalescent antibody responses may differ in efficacy study continued to shed virus despite having neutralizing antibodies.Given that a hallmark of COVID is lymphopenia, isotype switching and affinity maturation, which depend on T cell help, may be impaired in this disease.