Convalescent Serum

RESEARCH QUESTION: For patients with new COVID-19 infection, how does the addition of convalescent serum (CS) affect the outcomes (1) severe disease (indicated by mechanical ventilation) and (2) inpatient death?


Convalescent Serum (CS) is currently under study as possible treatments for COVID-19. Before randomized clinical trials read out, a retrospective observational study can provide insight into the efficacy of this treatment.

Study Design

The study examines the effect of CS treatment in hospitalized COVID-19 patients on disease severity. The study involves two study groups (those receiving or not receiving CS), as depicted below:

Convalescent Serum cohort pathways

Four outcomes are considered:

  1. Discharge without invasive mechanical ventilation (IMV) during stay
  2. Discharge after IMV during stay
  3. Inpatient death without IMV during stay
  4. Inpatient death following IMV during stay

The study uses mechanical ventilation as a proxy for severe but non-fatal disease. The outcome is retrospective over the entire patient visit and capture the worst severity of illness during the visit. For example:

  • Patient is put on a ventilator (category 2) and then succumbs to the disease (category 4); the outcome is category 4 (death).
  • Patient is temporarily put on a ventilator (category 2), then taken off the ventilator (category 1) and discharged; the outcome category 2.

The protocol only considers laboratory-confirmed cases. It specifically focuses on severe or life-threatening COVID-19 or judged by a healthcare provider to be at high risk of progression to severe or life-threatening disease.

Study Populations

Study Period: April 1, 2020 - Present

Index date: COVID-19-positive-date