Similar title to Kryazhimskiy, S., Dieckmann, U. ORCID: https://orcid.org/0000-0001-7089-0393, Levin, S.A., & Dushoff, J. (2007). On State-Space Reduction in Multi-Strain Pathogen Models, With an Application to Antigenic Drift in Influenza A. IIASA Interim Report. IIASA, Laxenburg, Austria: IR-07-051