Alaina Bell took a deep breath and held it Thursday, just like her grandma Sandra Hall told her to.

And before she needed to exhale, the injection was over - the 4-year-old had received her first dose of the swine flu, or H1N1 vaccine.

But for the inoculation to be effective, Alaina will need another shot in 21-28 days, said Howard Gamble, Wheeling-Ohio County Health Department administrator.

''Studies have shown the younger age groups don't get an immune response (from one shot). They have to get a booster. The first shot primes the immune system, and the second gets the antibodies - that's how the body fights infection,'' said Dr. William Mercer, Wheeling-Ohio County health officer.

Second shot clinic dates, Gamble noted, will be released when they are set.

Alaina is the daughter of Mark and Holly Bell of Wheeling. Mark Bell accompanied his daughter to the clinic. Alaina was one of the 200 children - ages 3-4 and 5-year olds not yet in kindergarten - who received the vaccine.

Gamble noted clinics for other priority groups will not be delayed because of the need for second shot clinics.

''The first second-shot groups will start in about two weeks,'' Gamble said, referring to students who were given the vaccine during a clinic held at Triadelphia Middle School. ''There is a 21- to 28-day window.''

During the Triadelphia Middle clinic on Oct. 26, more than 600 students from Triadelphia and Steenrod and Woodsdale elementary schools were inoculated.

On Wednesday, about 45 children were vaccinated during a clinic for children with high-risk medical conditions. And a student clinic Saturday at The Linsly School inoculated more than 600.

Mercer said if a child's arm is sore from receiving a shot, ice can be applied. And, if necessary, Advil can be given, but not aspirin because of the possibility it may lead to Reye's Syndrome, a potentially fatal disease. Some studies have shown, he noted, that Tylenol may diminish the effects of the inoculation.

Meanwhile, three more student swine flu vaccination clinics have been scheduled in Ohio County:

• For students of Bridge Street Middle School, Elm Grove and Middle Creek Elementary School, 3:30-8 p.m. Tuesday at Bridge Street Middle School Gym.

• For students of Warwood Middle School, Corpus Christi, Warwood and West Liberty Elementary School, 3:30-8 p.m. Thursday at Warwood Middle School Gym.

• For students of Wheeling Park High School, 9 a.m. to 2 p.m. Nov. 14 at WPHS Activities Center.