Healthy children between the ages of three and 10 will likely need only one half-dose shot of swine flu vaccine, says P.E.I.'s chief health officer.

Chief Health Officer Heather Morrison says authorities will continue to monitor immunity in young children. (CBC)

Young children are receiving a half-dose of the vaccine, and health authorities had planned to give a second half-dose three weeks after the first. But the Public Health Agency of Canada has released clinical trial results from Europe that show a single half-dose gives protection from swine flu for healthy children older than three.

"I certainly wouldn't want to bring my children back if I didn't have to," Chief Health Officer Dr. Heather Morrison told CBC News Thursday.

Two groups of young children will still need to get two needles 21 days apart. Children between six months and three years and those over three with chronic health conditions such as diabetes or asthma will be lining up for another half-dose.

Morrison said if data from ongoing clinical trials, both national and international, show immunity in healthy children between three and nine starts to fade over time, then those children will get a second dose.

"If any of that information shows that the immunity starts to wane in this healthy age group between three and nine, then parents will be notified immediately and we'll put the call out to bring them in for a second dose," said Morrison.