Weekly Epidemiological Record 5th August 2016 is available at: http://www.who.int/wer/2016/wer9131/en/ In this issue: - Update on vaccine-derived polioviruses worldwide, January 2015–May 2016 - Environmental isolation of circulating vaccine-derived poliovirus after interruption of wild poliovirus transmission, Nigeria, 2016 Full text at: http://www.who.int/entity/wer/2016/wer9131.pdf?ua=1