Influenza: a unique problem in vaccination

The genetic attributes of the influenza virus lead to unique problems in vaccination. First, a highly mutable RNA genome, resulting in sequential antigenic variation, could potentially manifest as a vaccine failure or epidemic influenza. Second, a segmented genome that engenders the virus with the capacity for genetic reassortment and the introduction of new antigens into a host population could possibly result in a pandemic. The core problem in combating influenza is the need for continual vaccine revision and induction of broader heterovariant immunity. Current vaccines – the conventional inactivated vaccine and the live attenuated vaccine – rely on technology of strain selection and production methods that is decades old. The immunity induced by these vaccines is dominated by the response to hemagglutinin (HA) and, therefore, the vaccines are most effective when there is sufficient antigenic relatedness between the vaccine strain HA and the circulating wild-type virus HA. Consequently, these vaccines a...