Federal health officials said 76 children have died from the H1N1 flu since the virus was discovered in April, which appears to be a higher rate than pediatric deaths caused by the seasonal flu.

Anne Schuchat, the director of that National Center for Immunization and Respiratory Diseases at the Centers for Disease Control and Prevention said that, by comparison, 46 to 88 children died each year during the past three influenza seasons.

She said she expected additional pediatric deaths from the H1N1 flu. While most of the children had underlying medical conditions, Schuchat said 20% to 30% of them did not.

The H1N1 virus has hit children and young adults at higher rates than older people, who are believed to have some sort of immunity from exposure to viruses linked to past influenza pandemics. So far most influenza illnesses are being caused by the novel H1N1 virus. However, health officials expect seasonal influenza strains to also start circulating more widely in the fall and winter months.

Earlier this week, the first vaccinations against H1N1 were given with MedImmune's flu mist nasal vaccine. Health officials said they expects shots to be available starting next week.

"We don't have enough vaccine available today for everyone who wants one," said Schuchat. "We do believe we will have ample supply of vaccine...in the weeks ahead."

The U.S. has purchased 95 million H1N1 vaccines and enough bulk ingredients from five companies to make up to make a total of 251 vaccine doses if needed. The vaccines are being distributed to states and some large cities, which in turn will distribute the vaccines to about 90,000 health-care providers, retailers and local health departments over a period of several weeks.

MedImmune, which is a unit of AstraZeneca PLC (AZN), makes a mist that's delivered through the nose and is approved for "healthy" people ages 2 to 49. It's not approved for use by pregnant women, who have been hit hard by the H1N1 flu. Pregnant women are being urged to get an H1N1 shot when they become available.

Other companies including a unit of Sanofi Aventis (SNY), Novartis AG (NVS), CSL Ltd. (CSL.AU) and GlaxoSmithKline PLC (GSK) are making H1N1 flu shots for the U.S. market. Last week, Sanofi said it started shipping vaccine to the U.S. government.

-By Jennifer Corbett Dooren, Dow Jones Newswires; 202-862-9294; jennifer.corbett@dowjones.com