The present invention relates to a novel hybrid/fusion protein derived from the CS protein of Plasmodium vivax (P. vivax), methods for preparing and purifying the same, its use in medicine, particularly in the prevention of malarial infections, for example those caused by P. vivax, compositions/vaccines containing the protein or antibodies against the protein such as monoclonal or polyclonal antibodies and use of the same, particularly in therapy. The invention also extends to lipoprotein particles of said hybrid protein and formulations/vaccines comprising the same and use thereof. In particular it relates to an immunogenic hybrid fusion protein comprising:a. at least one repeat unit derived from the repeating region of a type I circumsporozoite protein of P. vivax, b. at least one repeat unit derived from the repeating region of a type II circumsporozoite protein of P. vivax, andsurface antigen S derived from Hepatitis B virus, or a fragment thereof.