At a noontime news conference Wednesday, health officials from the Centers for Disease Control and Prevention said there would be plenty of flu vaccine to go around, with no shortages.
Speaking at the news conference, Dr. Jeanne Santoli, deputy director of immunization services at the CDC, said that 40 million doses of flu vaccine have already been distributed to as many physicians and clinics as possible.
"Almost all providers have some vaccine," Santoli said. "And more vaccine will be arriving throughout the season, and we believe there will be more than ever before."
But these assurances failed to convince many doctors. Distribution hasn't gone smoothly. Some doctors say the flu vaccine has shown up in commercial chain stores but has yet to reach their offices and patients.
Many providers have received partial shipments of the flu vaccine but have not received enough doses to cover all the patients in their practices.
Although the CDC said "not to worry," many doctors made it clear to ABC News that they are uncomfortable with the current shortage and disagree with Santoli's attempts to reassure.
"I think that the distribution system is inefficient and not well planned out," said Dr. John Sutherland, executive and program director for the Iowa Medical Education Foundation.
"I have had patients upset over the last two weeks, but we can't vaccinate them."
While acknowledging that some providers are getting the vaccine sooner than others, Santoli said Wednesday that "we still have the very best chance possible for protecting children and their families by vaccinating them, even if the vaccination isn't completed by the end of November" or even in January.
But many doctors disagree with that timetable and have grown frustrated by what seems a departure from previous CDC recommendations.
"Just a few years ago, the CDC was encouraging doctors to administer flu vaccines in September or early in the season," said Dr. David West, program director at St. Mary's Family Medicine in Grand Junction, Colo.
"This year, the CDC is telling us that vaccinating in January is adequate! Which CDC is telling the truth?"
The CDC acknowledges that higher-risk groups, such as young children and the elderly, need to be vaccinated as soon as possible.
Children who are being vaccinated for the first time require two doses of vaccine, and it takes at least two weeks for the kids to become immune to the flu virus.
The American Academy of Pediatrics has issued a statement saying flu season usually peaks between late December through March, so children will still benefit greatly from receiving the vaccine in December, January and beyond.
The AAP statement also advised pediatricians to send letters to parents explaining the current shortage and asking them to bring their children in for vaccinations later in the year.
Santoli said yesterday that if health care providers vaccinate their patients now and as more vaccine becomes available, there will be sufficient time to properly vaccinate children before flu season begins.
Santoli could be correct, some experts said. Flu season varies from year to year, and some years it's begun as late as February, but usually it's December. And in past years, flu season has started as early as October.
If folks are vaccinated too late in the game, they won't be protected. And the flu can be a deadly virus.
"I believe these delays in the manufacture and distribution of vaccines are potentially harming public health," said West.