Just How Many Shots Are On The CDC Schedule?

In any given vaccine, there will be one or more antigens. A vaccine that contains only one antigen is called monovalent. Examples include the Hiberix, ActHib and PedvaxHib vaccines, each of which contains a single antigen for Haemophilus influenzae type b, a bacterium that can cause meningitis. This single antigen can also, however, be combined into a polyvalent (or multivalent) vaccine such as Pentacel which adds antigens for diphtheria, tetanus, acellular pertussis and inactivated polio; Pentacel contains five antigens in total, hence its name.