Influenza in immunocompromised individuals is associated with an increased severity of disease [54] and HIV is recognized as a co-morbidity for 2009 H1N1 influenza [54, 80] . The rate of HIV in females are approaching that of males worldwide [81] . HIV RNA levels are consistently lower in women than men [82] . However, women have a 1.6-fold higher risk of progression to AIDS than men with equal viral loads [83, 84] . There also are gender disparities in access to care for women with HIV, with women traditionally having greater difficulty accessing treatment [85, 86] . Whether infection with HIV and progression to AIDS differentially affects the outcome of influenza virus infections in males and females has not been evaluated.