The optimum titers play a pivotal role for the success of CPT;in the ICMR study, they have only mentioned that the titers were detectable but the percentage is high, moderate and low titers has not been mentioned. On the question of neutralising antibody titers, IgG titers are typically associated with the severity of disease and decline in the early convalescent phase in less severe forms of the disease. In the PLACID trial, most of the donors (94.2%) had mild disease. Moreover, the fact that antibody titers were not measured in CP before transfusion, due to lack of validated and reliable commercial tests for qualitative or quantitative antibody measurement, could be another key confounding factor. The heterogeneity of the PLACID trial across its 39 study sites, especially in the severity of disease of enrolled participants, estimation of nAB (timing and method), and the "Standard of Care," could impinge on the reliability of the study data. Further, in the ICMR study, 67.9% of CPT group are PCR negative by day 7 when compared to 54.6% of non-CPT. This perhaps can be considered as beneficial impact of CPT which helps in decreasing community transmission. This data can also be used to tighten the discharge criteria to enable faster discharges, thus improving the availability of beds for a worsening pandemic. Notably, the dosage of CP administered is also variable. Some trials are administering doses as high as 600 ml, in single infusions or divided doses, up to five transfusion sessions. The consensus about effective CP dose is yet to be elucidated.
Convalescent plasma therapy in COVID-19: does it merit a deeper probe?