There have been numerous very disappointing results of Convalescent Plasma Therapy (CPT) in active infections with COVID-19 virus, raises a question of how to account for this, given the huge history of seeming benefit of CPT in a variety of infectious diseases over more than the past 100 years. We propose the following as a possible explanation, based on our experimental evidence. In CPT there is a collision between developed desirable viral resistance promoting hyper-immune antibodies and undesirable convalescent exosomes antigen (Ag)-specifically suppressing cellular immune responses stimulated by the prior now recovered acute viral disease. These inhibiting exosomes, that act to suppress Ag presenting cells and anti-COVID-19-Ag-specific effector T cells, are appropriate to convalescence, but when given early in infection may interfere with endogenous early developing profitable cellular immune anti-viral responses. To account for the high incidence of the Long Haulers post COVID patients, we postulate that these are due to immune reactivity to Ag remnants of the virus and not residual infection. These are postulated to held by and augmented by remnants of highly pathogenetic neutrophil extracellular traps (NETs). We propose that CPT with its content of potential broadly COVID Ag-specific suppressive exosomes be considered for possible effective treatment of the COVID-19 Long Hauler Syndromes. This certainly is so compared to the purported value of therapy with vaccines, as the diverse Ag-specific extracellular vesicles in the convalescent plasma would be an inhibitory influence on multiple COVID Ag-specific responses, beyond just to the spike protein of the virus.