A method of inducing either a T.sub.H1 polarized immune response, a T.sub.H2 polarized immune response or a combined T.sub.H1 and T.sub.H2 response to an antigen and associated vaccine formulations are disclosed. A method is provided for inducing a polarized T.sub.H1 response by parenteral administration of microparticles sized such that at least 50% of the microparticles are less than 5 .mu.m. The microparticles containing antigen entrapped or encapsulated by a biodegradable polymer. Additionally, a method is provided for inducing a polarized T.sub.H2 response by parenteral administration of nanoparticles sized such that at least 50% of the nanoparticles are less than 600 nm, the nanoparticles containing antigen entrapped or encapsulated by a biodegradable polymer. Vaccine formulations containing the B. pertussis antigens PTd, FHA or a combination of PTd and FHA are provided.