A regional shortage of seasonal flu vaccine mirrors a national shortage and ties a new knot in an already tangled influenza year.

But it's a knot that should loosen in the weeks ahead as more seasonal flu vaccine ships.

Both Carilion Clinic in Roanoke and Lewis-Gale Medical Center in Salem reported shortages Tuesday of the seasonal flu vaccine and are focusing first on vaccinating members of their medical staff and other employees.

Some CVS Pharmacy and Walgreens stores in the region are out of the seasonal flu vaccine, based on random phone calls made Tuesday. Calls to three Kroger pharmacies in the Roanoke Valley determined that each had remaining stocks of seasonal flu vaccine, according to pharmacy staff.

But Carl York, a spokesman for Kroger, said supplies are running low.

"We'll probably be out by the weekend," York said. "We've gone through a bunch of vaccine."

Robert Elfinger, a spokesman for Walgreens, advised people seeking seasonal flu shots to "call ahead first."

Meanwhile, shortage-related repercussions should be few, according to Dr. Thomas Kerkering, chief of infectious diseases for Carilion Clinic.

"At the moment, there is not an overtly negative implication of a shortage of seasonal flu vaccine," Kerkering said. "That is because we do not yet have seasonal flu in the area."

Seasonal flu is also referred to as "common flu" and "winter flu."

Both nationally and in Virginia, he said, "97.7 percent of all influenza isolates in the last few weeks have been the 2009 H1N1," also known as swine flu.

Infectious disease experts have said most people should receive vaccinations for both seasonal flu and H1N1 flu. The first doses of H1N1 vaccines are going to health care providers, emergency responders and others with close contact with patients or vulnerable groups.

"Yes, it would have been nice to have all of the seasonal flu vaccine available the first week of September, when it usually arrives, but at this point there are no adverse effects to the individual or public health because of the shortage," Kerkering said.

Nancy May, a spokeswoman for HCA Southwest Virginia and Lewis-Gale Medical Center, said physicians' offices "do not have any more of the shot form of the vaccination but do have some doses of the nasal mist form of the seasonal flu vaccine."

She said about 93 percent of Lewis-Gale's employees have received the seasonal flu vaccine and that there is sufficient supply to also vaccinate people who are admitted to the hospital.

Kerkering and others attribute the shortage, in part, to vaccine manufacturers working to produce the H1N1 vaccine in short order.

Thomas Skinner, a spokesman for the Centers for Disease Control and Prevention, said vaccine manufacturers have had to "readjust the timeline for delivery due to producing 2009 H1N1 vaccine, so some providers may have not received their seasonal vaccine yet."

"People may have to look around for [seasonal flu vaccine], but hopefully everyone who wants to get vaccinated will be able to," he said.

The CDC cites additional factors driving the shortage, including increased demand by more providers for the seasonal vaccine likely because of extensive media coverage about the H1N1 flu.

May said many providers probably under-booked vaccine orders based on demand in years past.

And the CDC reported that the largest supplier of seasonal flu vaccine, Sanofi Pasteur, "is experiencing a delay in their shipments."

The CDC said about 77 million doses of seasonal flu vaccine had been distributed nationally as of Oct. 2 -- which is about 61 percent of the doses expected to be distributed this flu season.

Elfinger of Walgreens said, "We've heard from some stores in some markets that they have run out of seasonal flu vaccine."

And he said some of those stores probably will not be restocked.

Elfinger noted that Walgreens had set a company record last year when it administered about 1.2 million seasonal flu vaccinations across its stores. But this year Walgreens has administered more than 4 million vaccinations, he said.

In an e-mail, CVS spokesman Mike DeAngelis wrote, "We are experiencing very high demand for flu shots across our markets and we are working closely with multiple suppliers to meet this demand on a day-to-day basis."

Neither DeAngelis nor Elfinger said they had specific information about the supply of seasonal flu vaccine at stores in the regional market.

"We would say call ahead," Elfinger said.

More seasonal flu vaccine should ship in the coming weeks, according to the CDC and others.

Kerkering said last year the flu season's peak was "epidemiology week nine, which is toward the end of February and beginning of March."