Advancing Treatment Options for Influenza: Challenges With the Human Influenza Challenge

Current therapeutic options for the treatment of influenza virus infections are limited. Only 2 classes of agents have licensed products, neuraminidase (NA) inhibitors and M2 inhibitors, and only NA inhibitors are active against currently circulating seasonal viruses. While observational studies show a benefi to f NA inhibitor treatment for hospitalized patients with influenza [1], optimal treatment for severely ill patients and those who are immunocompromised will likely require additional treatment options with a different mechanism of action. Since the 1918 pandemic, convalescent serum or plasma from persons previously infected with influenza virus has been investigated as treatment for individuals with severe influenza virus infection, including, more recently, individuals with human avian influenza and 2009 pandemic A(H1N1) infections [2, 3]. However, receipt of convalescent serum can be associated with severe adverse effects, and the resources necessary to produce such serum in large quantities are prohibitive [2]. Compared with convalescent serum, human monoclonal antibodies (mAbs) against influenza viruses may be more feasible for widespread use, without the adverse effects associated with human blood products. However, identifying a human mAb that can reproduce the clinical anti–influenza virus effects of polyclonal convalescent serum is a challenge. A handful of mAbs against influenza virus proteins are currently in early phases of evaluation for human use [4]. In this issue of The Journal of Infectious Diseases, Ramos et al report results from ah uman influenza challenge study evaluating the effect on clinical illness of a human mAb targeting the external portion (ie, ec