Use of convalescent plasma in COVID-19 treatment: is clinical severity more important than the intervention?

Objective: This study compared the outcomes of two cohorts of patients with coronavirus disease 2019 (COVID-19) who received COVID-19 convalescent plasma transfusions between 2020 and 2021.

Methods: This retrospective study was conducted at a tertiary hospital in São Paulo, Brazil. We included a retrospective cohort of patients who received convalescent compassionate plasma, and another group of patients from a previous clinical study. We collected clinical and laboratory data on the day of and 5 days after transfusion. Patients with hematological or immunological conditions were excluded. Statistical significance was set at p<0.05.

Results: COVID-19 convalescent plasma did not affect the outcomes of patients with severe COVID-19 when comparing the two cohorts transfused with different volumes and titers of neutralizing antibodies. Despite improvements in some laboratory parameters, no effect on clinical outcomes was observed. Dialysis negatively affected the length of intensive care unit stay, hospitalization, and mechanical ventilation use. Each higher point on the day 0 World Health Organization scale reduced the probability of hospital and intensive care unit discharge and the risk of mechanical ventilation discontinuation.

Conclusion: Dialysis and the assessed clinical severity represented by the World Health Organization scale on day 0 influenced the outcomes, whereas COVID-19 convalescent plasma transfusion did not.