Pregnant women at front of H1N1 vaccine line

ATLANTA (Reuters) - Pregnant women should be the first to get vaccinated against the new pandemic H1N1 influenza virus, federal health experts told a U.S. advisory panel on Wednesday.

Pregnant women are at special risk from the new strain, and vaccinating them protects their newborns, too, Dr. Anthony Fiore of the U.S. Centers for Disease Control and Prevention told a meeting of vaccine advisers to his agency.

He said a CDC working group has designated 42 million Americans who should be vaccinated first -- pregnant women, people with an infant too young to be vaccinated in the household, healthcare workers, children aged up to 4 years and children with chronic conditions making them at high risk of flu complications.

The committee was to issue its recommendations later on Wednesday.

Five companies are making H1N1 vaccine for the U.S. market -- AstraZeneca's MedImmune unit, Australia's CSL Ltd, GlaxoSmithKline Plc, Novartis AG and Sanofi-Aventis SA. It is not clear how many doses of vaccine will be available.

"Seasonal influenza vaccination should begin as soon as it is available for all groups currently recommended for seasonal vaccine," Fiore told the Advisory Committee on Immunization Practices.

He said seasonal and pandemic vaccines can be administered on the same visit but noted that trials in human volunteers are looking at the question and the advice may be changed later.

Fiore also released new CDC data showing that obese people do not have an especially high risk of death or complications from swine flu, as some earlier studies had suggested.

Fiore said the working group was assuming that people will need two doses of vaccine to be fully protected, but the clinical trials are also looking at this issue.

When giving vaccine, clinics should assume that more supply is coming, Fiore said. "If you vaccinate somebody in that initial target (group), don't go set aside in your mind or your refrigerator that second dose," he said. "You worry about that when the person comes back."

The U.S. government has taken delivery of 20 million doses of a vaccine against the new pandemic H1N1 swine flu, has ordered a total of 195 million doses and should be ready to start an immunization campaign in October, said Robin Robinson of the U.S. Department of Health and Human Services.

Data from human trials of the new vaccine, which have just begun, will not be available until late September, officials said.

H1N1 swine flu is now so widespread that the World Health Organization has stopped counting individual cases. Health experts are afraid it could worsen, especially when the Northern Hemisphere's influenza season starts in the autumn.

(Writing by Maggie Fox in Washington; Editing by Doina Chiacu)