Title:Thermostable Subunit Vaccines for Pulmonary Delivery: How Close Are We?
VOLUME: 22 ISSUE: 17
Author(s):Camilla Foged
Affiliation:Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Keywords:Thermostable, vaccine, adjuvant, drug delivery, nanomedicine, pulmonary administration.
Abstract:In the past century, vaccines have contributed to a significant improvement in global public health by
preventing a number of infectious diseases. Despite this, the vaccine field is still facing challenges related to incomplete
vaccine coverage and persistent difficult vaccine targets, such as influenza, tuberculosis, and Ebola, for
which no good universal vaccines exist. At least two pharmaceutical improvements are expected to help filling this
gap: i) The development of thermostable vaccine dosage forms, and ii) the full exploitation of the adjuvant technology
for subunit vaccines to potentiate strong immune responses. This review highlights the status and recent advances
in formulation and pulmonary delivery of thermostable human subunit vaccines. Such vaccines are very appealing
from compliance, distribution and immunological point of view: Being non-invasive, inhalable vaccines
are self-administrable, can be distributed independently of functioning freezers and refrigerators, and can be designed
to induce mucosal and/or cell-mediated immunity, which is attractive for a number of diseases requiring stimulation of local mucosal
immunity for protection. However, the design and delivery of thermostable dry powder-based vaccines represents a technological
challenge: It calls for careful formulation and dosage form design, combined with cheap and efficient delivery devices, which must be
engineered via a thorough understanding of the physiological barrier and the requirements for induction of mucosal immunity. Here, I review
state of the art and perspectives in formulation design and processing methods for powder-based subunit vaccines intended for pulmonary
administration, and present dry powder inhaler technologies suitable for translating these vaccines into clinical trials.
