Abstract: A method of stimulating an immune response in a subject including administering a micrometer-sized particle coupled with an antigen to the subject, wherein increasing the aspect ratio of the micrometer-sized particle increases the immune response. A method of stimulating an immune response in a subject including administering to the subject a plurality of particles, wherein each particle is coupled with an immuno stimulating agent and a protein. A vaccine particle composition including a plurality of particles configured to release a first protein at a first rate and a second protein at a second rate and configured to provide priming and boosting capability in a single dose.