Influenza viral infection is a common cause of respiratory illness among HIV-infected persons in whom it can be more severe and prolonged.9 HIV has also been described as the most common underlying risk factor in patients with respiratory infection.10 Influenza virus co-infections in HIV-infected patients cause a 4–8 times higher incidence of hospitalisation and death compared to non-HIV-infected individuals.11 The reduction in the number of CD4 T-cells due to infection with HIV causes immunodeficiency and thus higher susceptibility to complications of influenza in HIV patients.12 The gene discussed is CD4; the disease is influenza.