Increased CRP (OR = 2.56, 95% CI = 1.67 to 3.91) and NLR (OR = 1.45, 95% CI = 1.01 to 2.10) were confirmed to be statistically significantly associated with an increased risk of developing sequelae overall and respiratory sequelae (OR = 3.03, 95% CI = 1.71 to 5.36 and OR = 2.01, 95% CI = 1.21 to 3.31, respectively), whereas no association with post–COVID-19 fatigue was confirmed. This evidence concerns the gene CRP and COVID-19.