The disclosure provides various immunogens comprising a repeat unit of saccharide of Klebsiella pneumoniae CPS, which has a formula selected from the group consisting of Formulae (I) to (VI) as described herein. Also provided are vaccines including one or more immunogens selected from Formula (I) to (VI) and methods of eliciting an immune response against a Klebsiella pneumoniae and preventing infection of Klebsiella pneumoniae by using an immunogen of the invention.
