# Time-Dependent Outcomes of Convalescent Plasma in Early COVID-19: A Single-Center Cohort with a Host–Pathogen Perspective

## TL;DR

This study found that convalescent plasma may be linked to better outcomes in early-stage hospitalized COVID-19 patients.

## Contribution

The study provides new observational evidence on convalescent plasma's association with lower mortality in early pandemic patients.

## Key findings

- CCP was associated with lower in-hospital mortality (25% vs 42%) and higher discharge rates (66% vs 50%).
- Age-adjusted models showed CCP was linked to reduced odds of death.
- Prognostic models confirmed CCP's association with better outcomes despite other treatments.

## Abstract

Background: Evidence on COVID-19 convalescent plasma (CCP) is mixed. We examined associations between CCP administration and in-hospital outcomes among patients hospitalized during early pandemic waves in Poland. Methods: We conducted a retrospective, single-center cohort study of adults hospitalized with COVID-19 between October 2020 and January 2021. Patients receiving CCP were compared with contemporaneous controls without CCP. Primary outcomes were in-hospital mortality and discharge alive. Requirement for invasive mechanical ventilation/intubation was summarized descriptively because timing of intubation was not reliably available. Group comparisons used χ2/Fisher’s exact tests and t-test/Mann–Whitney U tests as appropriate. Associations with mortality and discharge were evaluated using logistic regression: (i) a prespecified age-adjusted model and (ii) an exploratory prognostic model including in-hospital treatments and severity markers (systemic glucocorticoids, remdesivir, oxygen therapy, and antibiotic use), interpreted prognostically rather than causally. Results: The cohort included 224 patients (CCP, n = 92; controls, n = 132); outcome status was missing for eight controls. Baseline demographics, comorbidities, and admission laboratory values were broadly comparable between groups. Crude in-hospital mortality was 25% in the CCP group (23/92) versus 42% in controls (52/124; p = 0.010), and discharge alive occurred in 66% versus 50%, respectively (p = 0.022). Invasive mechanical ventilation/intubation was required in 12.0% of CCP recipients and 4.5% of controls (p = 0.071). In age-adjusted models, CCP was associated with lower odds of in-hospital death. In exploratory prognostic models incorporating systemic glucocorticoids, remdesivir, oxygen therapy, and antibiotic use, CCP remained associated with lower odds of death and higher odds of discharge alive. Conclusions: In this early-wave retrospective cohort, CCP administration was associated with lower in-hospital mortality and higher discharge rates. Exploratory analyses adjusted for concomitant in-hospital therapies and severity markers should be interpreted as prognostic associations rather than evidence of causal efficacy.