Genetic Variation in the Immune Response Genes and Susceptibility to Severe COVID-19 in Nigerian Patients

Variability in COVID-19 clinical outcomes is partly attributable to host genetic factors influencing immune response, antiviral defence, and inflammatory regulation. While several European and Asian GWAS have identified susceptibility loci for severe COVID-19, the genetic architecture of severe disease in Nigerian populations is poorly characterised. This study investigated the association between genetic variants in immune response genes and susceptibility to severe COVID-19 in Nigerian patients. A case-control design enrolled 200 PCR-confirmed COVID-19 patients stratified as severe (requiring supplemental oxygen or intensive care) and mild-moderate, alongside 200 healthy controls from Ogun and Lagos States during the second and third waves of the pandemic (2021 to 2022). Targeted genotyping was performed for variants in IFNAR2, TYK2, OAS1, LZTFL1, and ABO blood group loci previously implicated in European GWAS. Chi-square tests and logistic regression adjusted for age, sex, BMI, and co-morbidities were applied. The ABO blood group A allele was significantly associated with severe COVID-19. The OAS1 p.Asp148Glu variant showed suggestive association. These findings represent the first host genetics study of COVID-19 severity in a Nigerian cohort. Keywords: COVID-19, host genetics, immune response, severity, Nigerian population