1. Biostatistics Research Branch, Division of Clinical Research, NIAID/NIH Bethesda, Maryland, U.S.A.
2. Department of Statistics and Data Sciences, The University of Texas at Austin U.S.A.
3. Department of Integrative Biology, The University of Texas at Austin U.S.A.
4. Department of Biostatistics, School of Public Health, University of Washington Seattle, Washington, U.S.A.
5. Vaccine and Infectious Diseases Division, Fred Hutchinson Cancer Research Center Seattle, Washington, U.S.A
6. Center for Inference and Dynamics of Infectious Diseases Seattle, Washington, U.S.A.