Porcine circovirus (PCV2) vaccine compositions comprising a peptide antigen derived from a PCV2 capsid protein are described. In various embodiments, the peptide antigen contains amino acids of the capsid protein from about amino acid 47 to about amino acid 202. In some embodiments, the peptide antigen is optionally linked to an artificial T helper epitope and/or mixed with T helper epitopes derived from the ORF1 and ORF3 proteins of PCV2. Methods of using PCV2 vaccine compositions are also described. In various embodiments, a vaccine composition is used in animals for the prevention of PCV2 infection. In other embodiments, a PCV2 vaccine composition is used as an antigen for diagnosing PCV2 infection.