Evaluation of SARS‐CoV‐2 antibody levels on hospital admission as a correlate of protection against mortality

Abstract

AbstractBackgroundMillions of people have now been vaccinated against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2). However, it is still unclear which antibody levels provide protection against mortality. It is further unknown whether measuring antibody concentrations on hospital admission allows for identifying patients with a high risk of mortality.ObjectivesTo evaluate whether anti‐SARS‐CoV2‐spike antibodies on hospital admission predict in‐hospital mortality in patients with coronavirus disease 2019.MethodsWe conducted a prospective, multicentre cohort study on 1152 hospitalized patients who tested positive for SARS‐CoV‐2 with a polymerase chain reaction–based assay. Patients were classified by vaccination status. Anti‐SARS‐CoV‐2 spike antibodies were determined on hospital admission. The investigated end point was in‐hospital mortality for any cause.ResultsSpike antibodies on hospital admission were significantly lower in non‐survivors in both non‐vaccinated (73 U/ml, 95%CI 0–164 vs. 175 U/ml, 95%CI 124–235, p = 0.002) and vaccinated patients (1056 U/ml, 95%CI 701–1411 vs. 1668 U/ml, 95%CI 1580–1757, p < 0.001). Further, spike antibodies were significantly lower in fully vaccinated and boostered patients who died compared to those who survived (mean 883 U/ml, 95%CI 406–1359 vs. 1292 U/ml, 95%CI 1152–1431, p = 0.017 and 1485 U/ml, 95%CI 836–2133 vs. 2050 U/ml, 95%CI 1952–2149, p = 0.036). Patients infected with the currently prevailing Omicron variant were three times more likely to die if spike antibodies were <1200 U/ml (OR 3.458, 95%CI 1.562–7.656, p = 0.001). After adjusting for potential confounders, this value increased to an aOR of 4.079 (95%CI 1.809–9.198, p < 0.001).ConclusionAnti‐SARS‐CoV2 spike‐antibody levels on hospital admission are inversely associated with in‐hospital mortality. Hospitalized patients with lower antibody levels have a higher risk of mortality.