(USA TODAY) -- Some parts of the country are experiencing spot shortages of flu vaccine because of increased demand in a flu season that started earlier and is more severe than previous years.

In Las Vegas, Celeste Tom tried six times before she found a flu shot for her boyfriend.

"I'd been bugging him to get a flu shot, but he kept putting it off," said Tom, 55. The Smith's Food and Drug Center where she got her shot was out. Her boyfriend called his doctor's office, but it was out, too. Next, she tried a Walgreens and then a CVS pharmacy; no vaccine. She called another Smith's, but it would administer the vaccine only to people 65 and older. On Monday she found a Walgreens that had 10 doses left. "I called back when he got off work at 1 p.m. to make sure they still had some, and he finally went in."

"There's vaccine out there," said Tom Skinner, spokesman for the Centers for Disease Control and Prevention. "There may be places where there are spot shortages, but there should be a little bit more coming, so people may have to check around."

It took Pam Copley a full day. The Staten Island, N.Y., mom, 42, tried her pediatrician, but the office had no appointments until February. She and her daughter Colleen, 15, got in line at a CVS, only to have the nurse say she didn't have shots for anyone under 18. After "a bunch of phone calls," Copley found vaccine at an urgent-care clinic. They had to wait there for five hours, but it was worth it, she said. "There's lots of flu in the schools here right now."

Manufacturers expect to produce 145 million doses this year, Skinner said. About 128 million doses have been shipped, he said. "We had 112million people vaccinated by the end of November."

"Spot shortages are not due to any manufacturing issues," said Rita Chappelle, a Food and Drug Administration spokesman. It's more an effect of a mild flu season last year and a more severe one this year, she said. "Demand for the vaccine is high."

There are two main vaccine producers in the United States, Sanofi US in Bridgewater, Conn., and GlaxoSmithKline in Upper Merion, Pa. For the 2012-13 flu season. GlaxoSmithKline (GSK) produced about 25 million doses of flu vaccine. All those doses are spoken for, spokesman Robert Perry said. That doesn't mean there's no more vaccine available. Much of GSK's production goes to medical suppliers that take orders from doctors' offices, he said.

It's tricky to estimate how much to produce, because flu vaccine takes six to nine months to make, so manufacturers have to plan before all the orders are in. GSK began taking orders for this flu season in October 2011. It will finish taking orders for next year's flu season next month.

Information on where the vaccine is available is at www.flu.gov.

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