Late Breaking Abstract - The affinity of haemoglobin for oxygen is not altered in the course of Covid-19

Abstract

<b>Context:</b> An <i>in silico</i> modelling suggested that SARS-CoV-2 might bind to haemoglobin (Hb). The authors hypothesised that this phenomenon could lead to a decreased oxygen (O₂) binding and also haemolytic anemia (Liu &amp; Li, <i>ChemRxiv</i> 2020). Although they were not supported by any experimental validation such as <i>in vitro</i> biochemical interaction, or any clinical observation, these conclusions were largely relayed in the media and social networks. The aim of this study was to investigate if Hb affinity for O₂ was altered in the course of Covid-19. <b>Methods:</b> In this retrospective, observational, single-center study, we compared the blood gas analyses of 100 Covid-19 patients (from March-April 2020) to those of 100 non Covid-19 patients (from March-April 2019). We also included in a third group 55 patients with carboxyhaemoglobin (HbCO) ≥ 8% (positive controls with altered Hb affinity). P₅₀ was corrected for body temperature, pH and PCO₂. <b>Results:</b> Patients were not statistically different for age or sex ratio in the Covid-19 and non Covid-19 groups. Median P₅₀ at baseline was 26 [25.2-26.8] versus 25.9 [24-27.3], respectively (<i>p</i>=0.42). As expected, it was lower in the high HbCO group: 22.5 [21.6-23.8] (<i>p</i>&lt;0.0001). When considering the time course of P₅₀, no significant difference was observed between Covid-19 and non Covid-19 groups, from day 1 to day 18. Median Hb concentration at beseline was 14 g.dl^-1 [12.6-15.2] in the Covid-19 group versus 13.2 [11.4-14.7] in the non Covid-19 group (<i>p</i>=0.006). On the 24 Covid-19 patients displaying anemia, none of them exhibited obvious biological haemolysis. <b>Conclusion:</b> There was no biological argument to support the hypothesis that SARS-CoV-2 could alter O₂ binding to Hb.