SEATTLE - Children and teenagers have joined the volunteers testing a swine flu vaccine in our area - one of eight places around the country doing the test trials.

One thousand adults are already being tested around the city. But now it's time to see how kids react to the different doses.

Fourteen-year-old Anna Bennett was one of those young people who took a shot to the arm in the fight to knock out the swine flu.

She's one of about 120 young people in the Seattle area - ages 6 months to 17 years old - who are part of a trial to test the new H1N1 vaccine.

"It affects a lot of people, and I know that a lot of people have died, and tons of people are getting infected," Anna says. "So it's important to do the studies."

The vaccine itself is already being stockpiled for distribution around the nation, even though the Centers for Disease Control say it's a month behind schedule making it.

The testing focuses on the amount of the vaccine to give people. Experts say that's why it's important to have specific studies involving children and teenagers.

"Because, in fact, most children's vaccines contain more antigen - more ingredients - than adult doses because kids' immune systems don't work so well," says Dr. Janet Englund of Children's Hospital.

As with any new vaccine, there are safety concerns - such as a bad reaction. But medical officials say this shot is very similar to the regular, seasonal flu shot. For those getting the vaccine, blood tests will help determine if it's working.

Anna's mom is proud that her daughter is taking part in the trial.

"It's exciting to think about the timeliness of this," says Sue Bennett. "Because the sooner they know how effective this vaccine is, the sooner it'll be ready for this next fall. So there's a sense of urgency, too, to being a part of it."

People young and old are stepping up for test vaccinations to prevent a monster flu season.

"I think it's gonna be safe," says Dr. Englund. "The real question is - is it going to work?"

The hope was to have 120 million doses by mid-October. Instead, there will be only be 45 million, with another 20 million each week after that.