SOMERS — “If you’re young, under 25, you should go get yourself vaccinated.”

That’s the advice from Carmel Ruffolo, University of Wisconsin-Parkside associate professor of biological sciences, who spoke about the H1N1 virus, commonly called the swine flu, Monday at Parkside.

Ruffolo said researchers are starting to look at the molecular level as to what happens when the virus enters the body.

“If I had to guess ... when the H1N1 comes into a younger, fitter body is that you have a massive immune response,” she said. “When our immune system reacts strongly to anything — anything being pollen, virus, bacteria, whatever — it can be lethal.”

And that’s why Ruffolo said young people should get vaccinated.

“You don’t play cards with influenza,” she said. “Influenza is a tricky virus. ... When you truly know your history of influenza, you don’t take chances with it.”

In reviewing previous flu pandemics, Ruffolo noted that the Spanish flu outbreak of 1918 infected half the population and killed more than 40 million people worldwide, most of them ages 20-40.

Vaccine availability is being limited to those most at risk: pregnant women, health-care workers, ages 6 months to 24 years, people who live with children 6 months or younger and children 5-18 who have chronic medical conditions.

The U.S. Centers for Disease Control reported that as of Nov. 6, widespread influenza activity was present in 48 states, with more than 17,000 people hospitalized. To date, there have been 672 deaths, including 19 in Wisconsin, which includes one in Kenosha County.

The World Health Organization said that, as of Nov. 1, 199 countries worldwide had reported confirmed cases of swine flu, with more than 6,000 deaths.

However, Ruffolo said that every year, 36,000 people in the United States die from regular flu and its complications, according to the National Institutes of Health.