New Approaches to the Prevention of Influenza

Abstract

Summary. More than 30 years after development of the first effective influenza vaccine, influenza remains virtually uncontrolled by human intervention. The explanation of this paradox is to be found in the nature of the causative virus, which is unique among infectious agents in its capacity for rapid and frequent intigenic changes. Therefor, the limited effectiveness of present day vaccines is less a problem in immunology than it is in the rapid obsolescence of vaccines. The continual need for “updating” of vaccines presents recurrent problems attendant upon the selection, development and production of new vaccine virus strains. Another problem, common also to most other inactivated vaccines, is the transient immunity induced by parenteral administration of conventional inactivated influenza vaccines, even if they are homotypic to the challenge virus. Thus, the problem of influenza immunization requires new approaches, and a variety of new currently under study. These approaches include: Better standardization of vaccines and increase in antigenic mass. This prosaic but necessary step has reduced one cause of vaccine failure of the past‐i.e. insufficient antigen. Better purification of vaccines to reduce toxicity related to non‐viral materials. Induction of local immunity by topical application of vaccine to the respiratory tract. It is logical to induce immunity at the site of subsequent challenge (as with live poliovirus vaccine), although the relative importance of humoral and local immunity in influenza has been insufficiently studied. Such immunity can be stimulated either by live or inactivated vaccines, but much more effectively by the former. Laboratory selection of antigenic mutants in anticipation of their selection in nature. This approach attempts to simulate in the laboratory the evolution of strain in the laboratory the evolution of strains in nature by passage of virus with antiserum. The objective is to accelerate the selection process so that a pan‐antigenic vaccine virus is derived that can protect against future variants of the subtye. Gentic manipulation of viruses by recombination and induction and selection of mutants.(The creation of new viruses with desirable properties.)