Federal health officials say pregnant women get good results from just a single dose of H1N1 flu vaccine, but young children still need two treatments.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Disease, says continuing studies confirmed both findings.

Dr. Anne Schuchat of the Centers for Disease Control and Prevention, told the same briefing that the flu is currently widespread in 48 states and hospitalizations and deaths continue to increase.

She said 30 million doses of the vaccine were available as of Monday. There will be continued challenges, she said, but the supply is expected to catch up with demand.

Dr. Bruce Gellin, director of the National Vaccine Program Office, reports that a program to monitor any side effects is now in place.