Research shows how FluMist elicits protection

New research from the Trudeau Institute in Saranac Lake, N.Y., may explain why the live attenuated influenza vaccine, also known as FluMist, elicits protection.
The journal article, titled "Live attenuated influenza vaccine impacts innate and adaptive immune responses," was authored by Trudeau Institute scientist Dr. Laura Haynes and her colleagues.
"Our research specifically examines how the vaccine, which is commonly known as FluMist, elicits protection," Haynes said. "Influenza infection normally induces a massive inflammatory response in the lungs that leads to significant illness and increases the susceptibility to secondary bacterial infections. The most efficient way to prevent influenza infection is through vaccination. To date, the mechanism of how FluMist induces protection has been unclear. Our study demonstrates that this vaccine works by inducing a very early non-specific immune response in the lungs in a mouse model of influenza infection."
The very early non-specific immune response sets the stage for an early influx of virus-specific immune cells, which are required for viral clearance. The immune response is protective against both non-matching and matching influenza strains and, as a result it could provide a level of protection in the case of a newly emergent influenza strain.
This very early immune response also serves to limit lung inflammation by significantly reducing inflammatory cytokine and chemokine levels produced following influenza infection. This novel finding provides insight into how this vaccine functions and is important because inflammation is a major cause of lung damage and can lead to secondary bacterial infections, which are common following influenza infection.
The study also shows that the LAIV vaccine also induced a robust immune response in health adult volunteers.
Subjects were recreated by the Naval Health Research Center in San Diego and were administered the commercially available FluMist vaccine. The immune response was then examined to the vaccine at specific time points following vaccination.