 ETEC is the type of E. coli that most vaccine development efforts are focused on . Antibodies against the LT and major CFs of ETEC provide protection against LT @-@ producing ETEC expressing homologous CFs . Oral inactivated vaccines consisting of toxin antigen and whole cells , i.e. the licensed recombinant cholera B subunit ( rCTB ) -WC cholera vaccine Dukoral have been developed . There are currently no licensed vaccines for ETEC , though several are in various stages of development . In different trials , the rCTB @-@ WC cholera vaccine provided high ( 85 – 100 % ) short @-@ term protection . An oral ETEC vaccine candidate consisting of rCTB and formalin inactivated E. coli bacteria expressing major CFs has been shown in clinical trials to be safe , immunogenic , and effective against severe diarrhoea in American travelers but not against ETEC diarrhoea in young children in Egypt . A modified ETEC vaccine consisting of recombinant E. coli strains over expressing the major CFs and a more LT @-@ like hybrid toxoid called LCTBA , are undergoing clinical testing . 
