The notice is taped prominently on the front door of the Cedar Glen group home, just below a wreath of dried flowers and leaves signaling fall. "While we love your company . . . " it begins.

What follows is a plea in bold, black letters: "If you have any cold or flu symptoms . . . please DO NOT VISIT us today."

For if the fall gives way to winter and Terry and Bob Sitz still have not been able to find flu shots for the eight elderly women who live at the home, a cough or sore throat or fever could quickly become an immediate danger.

In this season of vaccine shortage, signs are the first line of defense for Cedar Glen and other assisted living facilities and nursing homes where millions of the country's frailest seniors live -- and where a virus such as influenza can rampage seemingly overnight.

Along with hospitals, they have been given top priority as the federal government tries to get all remaining supplies of vaccine to the places needing it most. But the system is working in fits and starts, and administrators at these facilities are extremely concerned. Despite the government's pronouncements that supplies are forthcoming, many have no firm commitments that they will receive anything -- or even leads on where else to look.

"We're begging," Terry Sitz confessed yesterday after a long, futile week. Forty shots would immunize every resident at the five homes that she, her husband and their partners run in Montgomery County. They'll settle for less.

"With eight doses, we could take care of one house, at least," Bob Sitz said.

Without doses, though, there are warnings on front doors and runs on hand sanitizer at neighborhood drugstores. One assisted living facility in the District removed every oscillating fan from hallways and residents' rooms, the better to avoid aiding airborne germs. A nursing home in Prince George's County ramped up housekeeping efforts to ensure that door handles, telephones, TV remote controls and elevator buttons -- the usual suspects in spreading sickness -- are wiped down much more frequently.

Surgical masks are being restocked, just in case. Isolation plans are being reviewed for the same reason.

Behind the scenes are the phone calls. In the Silver Spring office of Maxim Healthcare, a major flu vaccine conduit, Jason Vollmer has a waiting list that is "growing every day" as worried nursing directors and their bosses search for a supply line. He doesn't offer false hope. Although he has just agreed to add two more facilities' names to the list, their chance of getting doses is, "unfortunately, very slim," he said.

Vaccine is moving into the pipeline, albeit slowly. The federal Centers for Disease Control and Prevention, working closely with Aventis Pasteur, the country's only current producer, sent an additional 4.2 million doses this week to high-priority targets throughout the country. That brought the reallocation total since early October to more than 9 million doses, with 16 million more still to be shipped, CDC spokesman Tom Skinner said late yesterday.

The numbers are meant to reassure people in high-risk groups, which comprise not only seniors but also adults with heart and lung disease, diabetes, asthma and other chronic conditions. Federal officials counsel patience and persistence. Yet Skinner acknowledged, "It's a very difficult situation."

The toughest part is getting vaccine to the right places. On Monday, the two largest long-term-care associations e-mailed a survey to their thousands of members to get a better sense of who had what in hand and who was completely lacking doses. "The importance of responding to this survey cannot be overstated," an accompanying note stressed.

But the CDC's Phase 1 and Phase 2 distribution plan signals the possibility that, even within this community, some facilities will be left out. Those awaiting orders from Chiron Corp., the company that had 48 millions doses thrown out because of contamination fears, are part of Phase 2. The quantity of Aventis vaccine that they ultimately will receive is a huge unknown.

The lucky ones include the Caton Merchant House in Manassas, which is part of the Prince William Health System and was taken care of through its inventory. Several Adventist nursing homes benefited when the local office of the Passport Health company canceled private and grocery-store immunization clinics and diverted some of that supply to them.

At Kensington Park, which only two weeks ago alerted the families of its residents that no shots were available, the 200 doses suddenly obtained were something "like a miracle" to nursing director Carol Milner. She had been relentless in her pursuit of them, putting the seniors complex on multiple waiting lists. When Vollmer phoned from Maxim with the good news Monday, Milner ran down the hall, burst into Executive Director George Oxx's office and yelled, "We got flu vaccine!"

On Thursday, the inoculating began. By 2:30 p.m., visiting Maxim nurses were setting up in the second of two assisted living buildings. "Vaccine central," Oxx declared as Milner and her assistant, Janice Martin, called out names alphabetically.

Mrs. Allen, Mrs. Bradley, Mrs. Bull, Mrs. Dawson.

"You could just imagine what would happen to some of these people" if influenza swept through the facility, Milner said.

That's what so worries Terry Sitz. Her group homes house men and women in various stages of memory loss. No matter how many times they are reminded, they don't necessarily remember to cough or sneeze into a tissue instead of their hands -- or to throw away the tissue rather than stuff it into their sleeve cuff.

"I want to feel hopeful, but I've been wanting to feel hopeful since I heard of the shortage," Sitz said yesterday, sitting in Cedar Glen's sunroom in Potomac and detailing the multiple efforts she has made. All, thus far, in vain.

First, she called Holy Cross, her usual supplier, which got only a fraction of its order and kept that to protect frontline workers.

Then, after reading of the easy availability of shots on Capitol Hill, she contacted U.S. Rep. Chris Van Hollen's office to ask whether 40 healthy staff members might be willing to turn over their vaccine to her elderly charges.

She even registered each resident in Montgomery's flu-shot lottery, though the woman who began taking their names over the telephone tried to discourage her. "She said, 'Why are you even doing this? Your chances are so low.' "

"I said, 'I have got to try,' " Sitz recounted. "I have frail people who cannot stand in grocery lines for five or six hours."

Kensington Park, a Montgomery County-operated seniors community, finally received vaccine. Resident John William Costello gets his. Anita Dore is among the women at a Potomac home run by Bob and Terry Sitz, in background, who hasn't had a flu shot. Terry Sitz has been trying to get vaccine from numerous sources.