(CBSNews.com) - A scramble for shots is under way as late-comers seek protection from a miserable flu strain already spreading through much of the country.
Federal health officials said Friday that there is still some flu vaccine available and it's not too late to benefit from it. But people may have to call around to find a clinic with shots still on the shelf, or wait a few days for a new shipment.
"We're hearing of spot shortages," said Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention.
Less than half of all Americans have received a flu shot.
In New York City a random sampling of a half-dozen pharmacies across Manhattan found all of them were out of the vaccine, CBS Station WCBS reports.
"If we can get as many people in the community vaccinated it means that there's less people around to get the flu and give it to everyone else" Dr. Mary O'Brien of Columbia University told WCBS.
In Boston, where Mayor Thomas Menino declared a public health emergency in response to the ongoing flu epidemic, lines were Saturday at flu clinics as residents took advantage of free flu shots being given out this weekend, CBS Station WBZ reports.
A total of 22 free public flu clinics were set up at city community health centers. Health officials estimated upwards of 6,000 people got flu shots on Saturday.
Manufacturers already have shipped nearly 130 million doses to doctors' offices, drugstores and wholesalers, out of the 135 million doses they had planned to make for this year's flu season. At least 112 million have been used so far.
The nation's largest manufacturer, Sanofi Pasteur, said Friday that it still has supplies of two specialty vaccines, a high-dose shot for seniors, and an under-the-skin shot for certain adults, available for immediate shipment. But it also is working to eke out a limited supply of its traditional shots - some doses that it initially hadn't packaged into syringes, said spokesman Michael Szumera. They should be available late this month.
And MedImmune, the maker of the nasal spray vaccine FluMist, said it has 620,000 extra doses available.
It does take two weeks for full protection to kick in. Still, health officials say it's a good idea to be vaccinated even this late, especially for older people, young children and anyone with medical conditions such as heart or lung diseases that put them at high risk of dangerous flu complications. Flu season does tend to be worst in January and February, but it can run through March.
The flu season is far from over, and as the U.S. Centers for Disease Control and Prevention declared this season an epidemic, physicians were urging people to take precautions against the flu virus.
"This is probably one of the worst flu seasons we've seen in close to a decade," said Kevin Most, a physician at Central DuPage Hospital. "We're seeing increasing numbers in our emergency rooms, we're seeing increasing numbers in our convenient care that are actually blowing the number of patients that we've seen in these past couple months out of the water when we look historically how many patients have been in."
What else can you do?
Wash your hands often, and avoid touching your eyes, nose and mouth. Viruses can spread by hand, not just through the air. Also, cough in your elbow, not your hand. When you're sick, protect others by staying home.
And people who are in those high-risk groups should call a doctor if they develop symptoms, added CDC spokesman Tom Skinner. They might be prescribed antiviral medication, which works best if given within the first 48 hours of symptoms.
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