Island health authorities have been forced to cancel a planned clinic to inoculate Island residents against swine flu, after the state was unable to live up to its assurance that it could provide enough vaccine for the job.

The clinic was to have been held on Nov. 11 at the regional high school. A clinic to provide vaccine against the regular seasonal flu will still go ahead at the high school on that day.

A meeting of the Island’s various town health agents, school nurses, tribe and other public health officials who comprise the Martha’s Vineyard Health Coalition reached agreement on the time and date last Thursday, having been assured earlier in the week by state officials that they could provide 7,000 to 8,000 doses of vaccine against the H1N1 or swine flu virus.

But the next day the state Department of Public Health contacted them and other health departments across the state, informing them that “adjustments” were being made to the amount of vaccine expected to be available, and the clinics could not go ahead.

The alert from the state thanked local officials for “your tremendous efforts and tremendous response in such a short time frame,” in organizing clinics.

It continued: “Within the past 48 hours, however, we have been alerted by the Centers for Disease Control and Prevention (CDC) that adjustments are being made to the amount of vaccine that is expected to be available to states in October and November.

“Public and school based clinics tentatively scheduled for November should be postponed indefinitely pending the availability of more specific information about vaccine production. We will provide additional information as it becomes available through the CDC.”

The state health department has since contacted the coalition, promising weekly updates on vaccine availability. It says it expects small quantities of vaccine to become available within a week, but warns that “depending on the amount available, some communities will receive the vaccine before others.”

Local health agencies will stockpile these small quantities until they have enough to distribute.

But when that might be remains uncertain. The state has scheduled a conference call with health coalitions around the state on vaccine planning for Nov. 9.

The problem is not with state authorities, but due to delays in the process of producing two vaccines: one against regular flu and one against H1N1.

Among the factors being blamed for the delays is the way it is produced. The process involves the use of millions of eggs as a medium to breed the viruses. Apparently the swine flu virus has proved more difficult to grow than was expected.

Meanwhile, local authorities have moved to plan B. Instead of the planned major clinic open to all people on the Island, they will target schools first.

It was agreed by the coalition on Wednesday that all children from preschool to grade 12, would be vaccinated over coming weeks, on a school-by-school basis, as supplies of vaccine allowed.

That decision, said coalition spokesman and health director for the Wampanoag tribe, Ron MacLaren, followed a meeting between the superintendant of schools Dr. James Weiss and the schools’ doctor, Dr. Michael Goldfein, where Mr. Weiss was urged to plan for vaccinations during school hours.

Mr. Weiss then presented the plan to the nurses and health agents.

There had previously been some disagreement among coalition members about whether the inoculations should happen during the school day or at special after-hours clinics.

The Vineyard Nursing Association, which will administer the vaccines, has been charged with meeting with each school over the next couple of weeks to work out logistics.

The argument for vaccinating during school hours was that it was likely to result in reaching larger numbers of students.

Health authorities consider it particularly important that younger people be vaccinated against H1N1. With regular seasonal flu older people are at greater risk, and therefore the main target group for inoculation. But swine flu has proven to be a greater problem among the young.

The Centers for Disease Control has nominated those between the ages of six months and 24 years old as a target group, along with pregnant women, people who live with or care for children younger than six months of age, and people aged 25 through 64 who are at higher risk for H1N1 because of chronic health disorders or compromised immune systems.

Older people wanting to be vaccinated against swine flu can contact their doctors, or wait until sufficient vaccine arrives for the health coalition to organize an H1N1 clinic.

Those seeking immunization against the regular flu can still attend the clinic to be held at the high school on Nov. 11, from 8 a.m. to noon.

Even though that clinic will now be only for regular flu, it still will operate differently from the way it has in previous years.

Instead of simply turning up at the high school for their shots, Islanders will be required to drive to one of two staging areas, at the Agricultural Hall in West Tisbury or Waban Park in Oak Bluffs, before being allowed to go to the school.

This measure is intended to even out the flow of people, and will serve as rehearsal for possible future emergencies on the Island.

Those arriving by means other than private car — such as bus, bike or on foot — can still go straight to the school.