Current vaccines suffer from several weaknesses, which may limit their application and reduce their efficacy. The limited stability of many vaccines is a first major problem, the logistics of these instable vaccines require a cold-chain and possibilities for stockpiling (e.g. pandemic preparedness) are limited. A second major problem is the fact that the majority of vaccines are still administered via injection, leading to issues varying from needle phobia to waste disposal. Finally, several vaccines suffer from poor immunogenicity.
For a number of vaccines, innovative formulations and alternative routes of administration may solve several of these problems. Advanced drying technologies such as spray-drying or spray-freeze-drying, combined with the incorporation of the vaccines in stabilizing sugar glasses, allows for the production of stable vaccine containing powders which do no longer require storage at lower temperatures. Such powders may further be processed into special dosage forms suitable for alternative routes of administration. Among these routes the pulmonary route of administration (inhalation) may be suitable for vaccination against airborne diseases.
In this presentation the possibilities of the new vaccine formulations will be illustrated by a range of different examples, including influenza, hepatitis-B and RSV vaccines. Further, results from preclinical in-vivo studies showing for which vaccines inhalation is a suitable route of administration and what the importance of the site of deposition in the lung is on efficacy will be discussed.