In addition to hollow microneedles discussed in Sect. 2, solid microneedles can be used to pierce the skin and thereby deposit vaccine in the epidermal and/or dermal space ). Techniques for vaccination using solid microneedles include the use of microneedles that penetrate the skin to make a hole through which vaccine can be transported. Vaccine formulations may be placed on the skin after microneedle penetration, coated onto microneedles or embedded within microneedles and released into the skin after insertion. Solid microneedles can be prepared as patches that can be easily applied to the skin, perhaps by self administration.