The efficacy of COVID-19 convalescent plasma (CCP) as a treatment for hospitalized patients with COVID-19 remained somewhat debatable; nevertheless, many studies have not investigated CCP confirmed to have a high neutralizing antibody titer was determined by a highly accurate assay. 23 118 patients receiving a single unit of CCP were stratified into 2 groups: those receiving high titer CCP (>250 50% inhibitory dilution, ID50; n=13,636) and those receiving low titer CCP (≤250 ID50; n=9482) to evaluate the correlation between CCP administration and titer determined by a live viral neutralization assay and 7- and 28-day death rates during hospitalization. Using multivariable Cox regression, risk variables were evaluated. Compared to non-intubated patients who received low titer CCP, non-intubated patients who received high titer CCP experienced 1.1% and 1.7% absolute reductions in 7- and 28-day death rates, respectively. No benefit of CCP was demonstrated in individuals who were intubated. The relative advantage of CCP with a high titer was confirmed by multivariate Cox regression. Administration of CCP with a high titer antibody content, as measured by a live virus neutralization assay, to non-intubated patients was linked with limited clinical effectiveness. CCP might have a role in the future if viral variations emerge that cannot be neutralized by current known therapies, even though its clinical utility was demonstrated to be minimal.