Multivalent vaccines: prospects and challenges.

The advantages and disadvantages of combination vaccines are set out with a clear indication that, although there are many (described and discussed) influences on in the immunogenicity of a vaccine it would still be of considerable value to be able to deliver such materials with the minimum number of needle-stick injections. Such a situation may become facilitated in the future as vaccines based on plasmid DNA become available; a prospect which is examined in outline in the final section.