Evolution of vaccine technologies and platforms. CMV, cytomegalovirus; GAS, group A Streptococcus; GBS, group B Streptococcus; HBV, hepatitis B virus; HCV, hepatitis C virus; HEV, hepatitis E virus; Hib, type B Haemophilus influenzae; HIV, human immunodeficiency virus; HPV, human papillomavirus; MenA, meningococcus A; MenACWY, meningococcus ACWY; MenB, meningococcus B; MenC, meningococcus C; Pneumo, pneumococcus; RSV, respiratory syncytial virus; SARS, severe acute respiratory syndrome; VLP, virus-like particles.