Vaccines are one of the most effective ways to reduce illness and death caused by infectious diseases. We often associate vaccines with childhood, but new vaccination strategies have the potential to protect adults from cancer and chronic diseases. This is thanks to emerging technology that helps turn recombinant viruses (formed by recombining genetic material) into antigens and immunotherapeutics. An antigen is any substance that causes the immune system to produce antibodies; immunotherapy treats disease by inducing an immune response. Research in these areas is expanding rapidly.