Ссылку нет, но источники приведу:Grassly NC, Fraser C, Wenger J, et al. New strategies for the elimination of polio from India. Science 2006;314:1150--3.; Grassly NC, Wenger J, Durrani S, et al. Protective efficacy of a monovalent oral type 1 poliovirus vaccine: a case-control study. Lancet 2007.