Despite these challenges, progress is being made in the creation of anti-adhesion vaccines. In animal models, passive immunization with anti FimH-antibodies and vaccination with the protein significantly reduced colonization by UPEC. Moreover, the "Bordetella pertussis" adhesins FHA and pertactin are components of three of the four acellular pertussis vaccines currently licensed for use in the U.S. Additionally, anti-adhesion vaccines are being explored as a solution to urinary tract infection (UTIs). The use of synthetic FimH adhesion peptides was shown to prevent urogenital mucosal infection by "E. coli" in mice.