IgG1/3 exhibit stronger binding affinity for C1q than IgG2/4, enhancing classical complement pathway activation (19); therefore, sera from individuals who recovered from DENV infection, with high IgG1 and IgG3 anti-E antibody titers, may exhibit stronger complement-mediated inhibition of ADE than that of sera from COVID-19-vaccinated individuals with elevated anti-E IgG2 and IgG4 titers. The gene discussed is IGHG3; the disease is COVID-19.