By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - Essential health care workers would be immunized first if a flu pandemic broke out in the United States, the government said on Wednesday.

The Department of Health and Human Services released long-awaited details on who would get vaccinated if and when a pandemic -- serious global influenza epidemic -- emerged.

The plan puts a million health care workers, such as emergency room staff and nurses, at the top. Next are military and "mission critical" personnel, public health workers and hospital and nursing home staff.

All of these play a "critical role in providing care for the sickest persons; highest risk of exposure and occupational infection," the plan reads.

"This guidance is the result of a deliberative democratic process," HHS Secretary Mike Leavitt said in a statement. "This document represents the best of shared responsibility and decision-making."

Mike Osterholm, an infectious disease expert at the University of Minnesota's Centers for Infectious Disease Research and Policy, said the plan did not do enough to protect critical workers.

While it designates people involved in making vaccines and drugs for flu, it does not account for other drugs such as insulin and antibiotics, he said.

"It does nothing to help support the manufacturing and transportation system for moving these drugs from offshore to the United States," Osterholm, who advised the government on the guidelines, said in a telephone interview.