Understanding Covid-19: Digit ratios and duration of oxygen therapy in hospitalized Covid-19 patients

Abstract

BackgroundCovid-19 severity shows a sex difference (males>females) and progressive hypoxia among the most seriously affected. Digit ratios are sexually dimorphic and may be negatively-related to prenatal (2nd-to-4th digits' ratio; 2D:4D) and pubertal (3rd-to-5th digits' ratio; 3D:5D) testosterone. Oxygen therapy is important in Covid-19 treatment and low 2D:4D is linked to efficient oxygen metabolism. We consider relationships between digit ratios and duration of oxygen treatment in hospitalized Covid-19 patients. MethodsDigit lengths were measured from photographs of the patient's hands. Age, Sex, BMI, vaccination status and number of days of O2 treatment, were recorded. ResultsThere were 100 (58 women) patients. Sex differences (males<females) were present in 2D:4D ratios (Dr-l 2D:4D; ǀDr-l 2D:4Dǀ) but not in 3D:5D. Positive relationships were found between 2D:4D variables (left 2D:4D, women and men; Dr-l 2D:4D women), 3D:5D (male left 3D:5D) and duration of oxygen therapy. After removal of the influence of age, BMI, vaccination status and sex there were positive relationships between 2D:4D (right and left) and duration of oxygen therapy but no such associations for 3D:5D. In addition to 2D:4D there was evidence for a positive relationship between BMI and oxygen therapy. ConclusionWe have found that high (feminized) 2D:4D of males and females is positively related to duration of oxygen therapy. This adds to the evidence for links between severity of Covid-19 and national and individual level variation in foetal androgen (as measured by 2D:4D). We discuss our finding in the light of the “low-androgen-driven COVID-19 pandemic theory”.