MARSHFIELD (WKOW) -- Marshfield Clinic has been leading federally funded vaccine research for almost 20 years.

"One of our most important studies is our study of influenza vaccine effectiveness. The CDC recommends that all adults and all children over six months of age be vaccinated every year against the flu," said Edward Belongia, director of Center of Clinical Epidemiology and Population Health at the Marshfield Clinic Research Institute.

Most people probably don’t think much about the flu vaccine when they roll up their sleeve for their annual shot, but at Marshfield Clinic a lot of time is spent working on the science behind flu vaccination.

"To find out how the vaccine is working we enroll around 2,000 people every year when they come in to see a doctor. For people that consent to be part of the study, we collect a swab from their nose and throat and then we test that swab for the flu virus. Then we find out their vaccination status and we compare the people who are vaccinated and unvaccinated and we can estimate how well the vaccine is protecting people against the flu," Belongia said.

Unique for one of the largest rural health systems in the US, The Research Institute at Marshfield Clinic has a very large and skilled research team tasked with enrolling patients and generating study data.

"Because the study is so large, we end up hiring on anywhere from 10-15 to help support our current staff. At any given time there is about 15 coordinators that are out there recruiting and enrolling patients being seen," said Deanna Cole, manager of Research Studies at the Marshfield Clinic Research Institute.

Then every February the World Health Organization meets to select the vaccine strains for the next flu season, where the data from study plays an important role in helping guide the vaccine strain selection.