Similar title to Adams, B. & Sasaki, A. ORCID: https://orcid.org/0000-0003-3582-5865 (2009). Antigenic distance and cross-immunity, invisibility and coexistence of pathogen strains in an epidemiological model with discrete antigenic space. IIASA Interim Report. IIASA, Laxenburg, Austria: IR-09-069