DENVER -- Some doctors are worried that new shipments of the seasonal flu vaccine will not come, causing a spike in flu cases over last year.

Dr. Rafer Leach, owner of Guardian Urgent Care in Denver, received a call from his distributor informing him that more than 1,000 seasonal flu shots that he has been waiting on, will not come, leaving him with only 50 shots for the entire flu season.

“That's at least what I was told, that it's not coming,” said Leach.

The Colorado Department of Health and Environment has insisted for months that shipments of the seasonal flu vaccine are on the way and that production has simply slowed due to production of the H1N1 flu vaccine.

Leach worried that the focus on distributing the H1N1 vaccine could backfire once seasonal flu starts spreading.

"I fear that we're going to just sort of rob from Peter to pay Paul and not have enough people immunized when the seasonal flu comes around," he said.

But public health officials insist there will be enough seasonal flu shots to go around.

"If your physician's office is out of [seasonal flu shots] right now, they will receive more," said Margaret Huffman, a public health nurse with the Colorado Department of Health in an interview in September.

Joni Reynolds, head of the state immunization program, said demand for the seasonal flu vaccine has outstripped supply but more is on the way. She said there's still plenty of time for people to get it before the worst of the seasonal flu hits, usually in the winter months.

Leach said he hopes his distributor is mistaken and there will be new shipments. He said otherwise, fewer people will wind up getting the seasonal flu vaccine, which could result in overwhelmed hospitals and clinics and a spike in the number and severity of flu cases.

"We just might have, perhaps, longer duration illness and more severe illness and more people with flu illness this year," said Leach.