Immunoprophylaxis in Biosecurity Programs

Abstract

In aquaculture, vaccination is a part of biosecurity measures. Vaccination reduces the risk of disease outbreak in the farm and spread of disease within the farm, to other farms, and to wild fish. Even nonvaccinated fish and poor responders may be protected as a consequence of herd immunity in the vaccinated farms. Prevention is achieved when the density of susceptible hosts is reduced sufficiently so that the basic reproduction number, the average number of secondary cases arising from a single primary infected individual, falls below 1. Based on the information about the basic reproduction number and the vaccine efficacy, the outcome of immunoprophylaxis can be predicted using modeling.