(44-20) 74 18 84 00 Fax (44-20) 74 18 84 16 E-mail: mail@emea. europa. eu http: / /www. emea. europa. eu ©EMEA 2007 Reproduction and/ or distribution of this document is authorised for non commercial purposes only provided the EMEA is acknowledged very large (over 70,000 infants) because it was designed to see if the vaccine caused a very rare, serious side effect called intussusception, a condition in which part of the bowel becomes enfolded within another part of the bowel, leading to a blockage.