1 Department of Medicine, Columbia University Medical Center, 177 Fort Washington Avenue, Milstein Hospital Building, 6C-12, New York, NY, USA. mjc2244@columbia.edu.
2 Department of National Disease Control, Ministry of Health, Kampala, Uganda.
3 Uganda Virus Research Institute, National Influenza Center, Entebbe, Uganda.
4 Laboratory of Epidemiology and Public Health, Yale University School of Public Health, New Haven, CT, USA.
5 Section of Pulmonary and Critical Care Medicine, Yale University School of Medicine, New Haven, CT, USA.