The live oral
polio vaccine was the first mucosal
vaccine accepted for general use. Since then, similar
vaccines have been developed against
typhoid fever,
cholera and
rotavirus infection, and a nasal
vaccine against
influenza has recently been registered in the USA. The only non-living mucosal
vaccine on the market today is an oral
cholera vaccine consisting of inactivated Vibrio cholerae and the B subunit of
cholera toxin. Several groups of scientists are at present working on the development of other mucosal
vaccines based on inactivated microbes or parts of them. Results from animal trials at the Norwegian Institute of Public Health, suggest that non-living nasal
vaccines can provide protective immunity and may be combined with the same types of
vaccines for injection. Clinical trials with nasal
vaccines consisting of
beta-propiolactone inactivated
influenza particles, showed that it was possible to achieve serum concentrations of
antibodies at levels providing protection against
influenza.
IgA antibodies, which were formed in nasal secretions, were specifically aimed at
influenza and ought to hinder the spread of the disease. By optimizing the immunization regimes so that the immunological memory is better exploited, and by adding adjuvants to the formulations, it is probable that non-living mucosal
vaccines can be realistic alternatives to several of the
vaccines now given by injection.