UPDATE 1-Too few in U.S. seek flu treatment, CDC says

* 26.6 million vaccines now produced

* Analysts say Obama risks credibility over delays

* Obama frustrated with vaccine delays (Adds analyst assessment of political risk)

By Maggie Fox, Health and Science Editor

WASHINGTON, Oct 30 (Reuters) - Only half of the people in the United States who most need immediate treatment for H1N1 swine flu are actually seeking it, even as the virus spreads at unprecedented speed, U.S. health officials said on Friday.

The latest count shows 114 children have been killed by the virus in the United States since April, during a time when there is usually virtually no influenza, said U.S. Centers for Disease Control and Prevention Director Dr. Thomas Frieden.

And while President Barack Obama expressed frustration over vaccine delays, analysts said his credibility was at risk if vaccination did not start to go more smoothly.

Frieden said H1N1 is widespread, and case counts continue to rise in most states.

"One of the things that we have been surprised to see is even among people who have underlying conditions such as asthma, heart disease or lung disease, only half sought care," Frieden told reporters in a briefing.

At the same time, emergency departments were crowded but often with people who did not need medical care, he said.

CDC researchers estimated this week that as many as 5.7 million people in the United States have been infected so far, with at least 1,300 deaths.

Frieden said the CDC had a cumulative 26.6 million doses of vaccine available -- far short of the 40 to 80 million that had been forecast for the end of October. Lines have formed outside clinics as people seek the vaccine.

The Health and Human Services Department had predicted 20 million doses would roll out every week but just 10 million have been produced in the past seven days.

CREDIBILITY GAP

"Frustration over swine flu vaccine availability has created a growing credibility gap for governments in the U.S., Canada, western Europe, Hong Kong and Japan attempting to vaccinate large portions of their population," Scott Rosenstein of political risk consultancy Eurasia Group said in a note.

"To date, the political fallout from this situation has been relatively minor," he added.