Kinetics of antibody response in critically ill patients with Middle East respiratory syndrome and association with mortality and viral clearance

The objective of this study is to examine the IgG antibody response in critically ill patients with the Middle East respiratory syndrome (MERS) and to examine the association of early antibody response with mortality and viral clearance. We collected blood samples from 40 consecutive real-time reverse transcription-polymerase chain reaction (rRT-PCR) confirmed critically ill MERS patients on ICU days 1, 3, 7, 14 and 28. MERS-CoV antibodies were detected by enzyme-linked immunosorbent assay (ELISA), using wells coated with MERS-CoV S1 antigen. Patients were admitted to ICU after a median (Q1, Q3) of 9 (4, 13) days from onset of symptoms with an admission Sequential Organ Failure Assessment (SOFA) score of 11 (6.5, 12). Among the study cohort, 38 patients (95%) received invasive ventilation, 35 (88%) vasopressors, 21 (53%) renal replacement therapy and 17 (43%) corticosteroids. Median (Q1,Q3) ELISA optical density (OD) ratio significantly increased with time (p