Finally . . .

We now have an intranasal vaccine for influenza on the market. The vaccine is made by reassorting the annual vaccine strains with a cold-adapted virus to create viruses that express the seasonal hemagglutinin and neuraminidase molecules but cannot grow at normal body temperature. As a result, the vaccine virus replicates only in the nasal passages where the environment is colder and therefore does not produce "flu."

The same seasonal strains that are selected for the parenteral vaccine are the source of the annual live, attenuated influenza vaccine (LAIV, or Flu-Mist®). When these live viruses are sprayed into the nose, they cause a limited, localized infection that induces both systemic and local immunity.

What advantages can you imagine using LAIV (more than one may be correct)?

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