CRP and COVID-19: The third major finding of this study is that the three biomarkers of Long COVID assessed in our study (CRP, KYN/TRY, and IR) or acute COVID-19 + Long COVID (CRP, KYN/TRY, IR, SpO2, and PBT) together explain a large part of the variance in the physio-affective phenome of Long COVID (around 40–41%).