Hoping to guard against an outbreak or worse of the H1N1 virus among young people this winter, a group that includes town health agents, the Vineyard Nursing Association and school leaders is moving forward with a plan to vaccinate the Island student population against the virus known as swine flu.

Members of the group have been meeting weekly to finalize a plan to distribute vaccine to the Martha’s Vineyard Regional High School and the five Island elementary schools.

The plan calls for making the vaccine available by late October or early November, before the start of the flu season, which usually runs from December through February.

It would mark the first time in decades that students would receive inoculations at school, underscoring the potential danger of a widespread swine flu outbreak.

Last week the World Health Organization issued warnings that swine flu — as opposed to seasonal flu, which targets the upper respiratory system — infects deep in the lungs, causing lesions and scarring. And unlike seasonal flu, which poses the greatest risk to the elderly, the median age of swine flu victims is 14.

In fact the only group found to be immune to swine flu are the very elderly — those born before 1918 who were exposed to the deadly Spanish flu.

The Island group working on the public school vaccination plan was formed to carry out a directive from the Massachusetts Department of Public Health to provide vaccinations to groups of people considered most at risk.

Those groups include pregnant women, caregivers of infants under six months of age, young people from age six months to 24 years, and people with chronic pulmonary disease, cardiovascular problems, kidney disease or any type of immune suppression issues.

State officials estimate that about half of all Massachusetts residents are in the target groups. Because most immune systems are unfamiliar with H1N1, a novel virus strain, two vaccinations, spaced a few weeks apart, are required.

Vineyard schools superintendent Dr. James H. Weiss said yesterday that the current focus is on inoculating young people and other high-risk groups with the hope of preventing the virus from spreading to the rest of the Island population.

“We are trying to accomplish two things: follow a state directive, but also be proactive and develop a plan to prevent the outbreak of a potentially deadly [virus]. Since one of the groups at risk is young people, it does make some sense to distribute the vaccinations at the schools they already attend,” Mr. Weiss said.

Edgartown health agent Matt Poole estimated there will be enough vaccine for approximately 3.4 million people in Massachusetts. He said it is still too early to say for certain, but that there could be as many as 7,000 or more vaccinations performed on the Island. The year-round population of the Vineyard is about 15,000.

Mr. Poole said in addition to the public school vaccination program, the vaccine will be available in doctors’ offices. He said the vaccinations will be paid for and provided by the state Department of Public Health with the assistance of the federal Centers for Disease Control.

The federal government has given Massachusetts $10.4 million to defray costs associated with vaccination drives. Most health insurers are expected to cover the cost of the vaccine obtained in a doctor’s office.

And while the prospect of vaccinating over half the Island population may seem daunting, Mr. Poole said his group can pull it off.

“It’s not going to be just us, it’s going to be a lot of people working together. Sure it will be a bit of a challenge; that is certain, but I am confident we will be successful. I think we have already shown we can do this with our annual [seasonal] flu vaccinations,” he said.

Robert Tonti, chief executive officer for the Vineyard Nursing Association, said there is the potential for public confusion since the upcoming seasonal flu vaccination is also scheduled for this month. An inoculation for seasonal flu will not prevent someone from getting H1N1. “It’s very important to make that distinction. We don’t want people to confuse the two,” Mr. Tonti said.

He said the seasonal flu vaccination at the regional high school has been moved up this year to Saturday, Sept. 26, largely to allow more time for health officials to focus on the H1N1 vaccinations.

The vaccinations will be voluntary, despite some erroneous reports circulating that anyone who refuses to be vaccinated will be quarantined.

Micaelah Morrill, budget and communications director for Cape and Islands Sen. Robert O’Leary, said the reports are untrue and could lead to needless confusion and discord over the vaccination issue.

“There are no mandatory vaccinations; they are entirely voluntary,” she said, adding: “There is a provision allowing the commissioner [of the Department of Public Health] to impose a quarantine under extreme circumstances, like the outbreak of a highly infectious or deadly disease . . . but that would not apply to someone who refused a vaccination.”