About 6,000 North Coast residents who are most vulnerable to the flu will be inoculated against the virus this weekend at five clinics stretching from Petaluma to Ft. Bragg.

But only Kaiser Permanente members and Mendocino County residents most in danger from flu will benefit from this latest influx of vaccine.

Beginning at 10 a.m. Saturday, Kaiser will dispense at least 4,000 flu shots to high-risk members at its medical offices in Santa Rosa, and more than 1,000 shots at its Petaluma branch, Kaiser representatives said.

Unlike thousands of North Coast residents who have scrounged fruitlessly for the shot, Kaiser members have benefited from the managed-care group’s pre-shortage decision to order vaccines from Aventis - U.S. health care providers’ lone alternative to Chiron.

“This year, fortunately, Chiron was not one of our suppliers,” said Rick Malaspina, spokesman for Kaiser’s Northern California region.

In Mendocino County, communicable disease experts have organized three simultaneous clinics Sunday for high-risk residents in Willits, Ukiah and Ft. Bragg and are expected to distribute most of the 1,350 vaccines provided by the state. Identification showing age and Mendocino County residency will be required.

The state has shipped 1,520 doses of vaccine to Lake County, where public health employees have begun taking reservations to inoculate about 700 high-risk seniors. The county does not plan walk-in clinics.

Meanwhile, throughout Sonoma County, public health officials have begun to make the first of 3,300 newly arrived doses of vaccine available to community clinics, hospitals and long-term care facilities.

“It keeps changing as we find out who’s getting vaccine through private channels,” said Dr. Leigh Hall, Sonoma County’s deputy public health officer. “We wanted to make sure that hospitals, emergency rooms and ICUs were covered.”

The public health department is working with Palm Drive Hospital in Sebastopol and Sonoma Valley Hospital in Sonoma to evaluate their needs, for example, Hall said.

The Kaiser clinics, the second of the season offered at each facility, may be the last this year.

For health care workers and caregivers of very young children or the chronically ill elderly, Kaiser’s Santa Rosa medical center also will dispense the nasal spray FluMist, a live influenza vaccine approved for healthy people ages 5 to 49.

The nasal spray will not be given Saturday in Petaluma, according to Kaiser.

The shots at the Petaluma clinic will be “first come, first served, and there will be spotters on staff walking through clinic lines to check for vulnerable patients so those can be vaccinated separately” to avoid lengthy waits, said Kaiser spokeswoman Carol Harris.

After Saturday, Kaiser’s Santa Rosa clinic will have vaccinated 10,000 members since the U.S. vaccine shortage was triggered last month by contamination at Chiron Corp.‘s Liverpool, England, plant.

In keeping with federal and state orders to ration flu vaccines, Kaiser will verify that shot recipients are among high-risk groups - including adults 65 and older; children 6 to 23 months of age; chronically ill patients 2 to 64 years old; pregnant women; and residents of long-term care facilities and nursing homes.

Thousands of seniors stood in the rain outside Kaiser’s Santa Rosa medical center Oct. 23, awaiting one of 5,900 flu shots given at the center’s first clinic this season.

Though communal settings for seniors are likely to receive much of Sonoma County’s public health vaccine allotment, Mendocino County is focusing more on seniors who live independently, public health nurse Jennifer Dutton said.

Mendocino County’s public health clinics will limit the vaccine to adults 70 years and older; emergency room, intensive care and neonatal intensive care doctors and nurses who are 50 years and older; and to residents 19 to 69 years of age with chronic medical conditions - including cardiac, respiratory and kidney disease, as well as insulin-dependent diabetes and people with suppressed immune systems.

“Each county had to make their own decision,” Dutton said. “We have a lot of seniors who are still ambulatory in our community. And if you have a 70-year-old who’s ambulatory and they get sick, they could spread the virus more.”

In Lake County, public health officials’ first priority is vaccinating residents 65 and older who have medical conditions. They’re also rationing more than 200 doses to skilled-nursing facilities, and ensuring that pediatricians who treat high-risk children get their share. Remaining doses will be offered to other seniors 65 and older and younger adults with chronic illnesses.

“We do not want people out in the weather in lines,” health officer Craig McMillan said Thursday. “We’re looking for a way they can come into the clinic for appointments.”

Typically, the health department dispenses 3,000 to 4,000 flu shots each year, and stocks that private Lake County providers receive will help cover that population, McMillan predicted.

“The doctors and the hospitals have another 3,000 doses out there either in their hands or coming to them,” he said. “So we’re pretty satisfied we’re going to get there.”