IGHE and COVID-19: In addition, the levels of serum anti-SARS-CoV-2–spike S1 protein-specific IgE (SP-IgE) and anti-SARS-CoV-2 nucleocapsid protein-specific IgE (NP-IgE) appear to be significantly higher in patients suffering severe COVID-19; and SP-IgE levels correlated with the total lung severity scores and the ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2) (54).