Children and pregnant women must be among the 160 million people who are first in line for swine flu shots, US officials have recommended. However they said they were unlikely to have enough vaccine for all of them.
The Centers for Disease Control and Prevention's Advisory Committee on Immunization Policy recommended after a day-long emergency meeting that five target groups, totalling around 160 million people who are at higher risk for disease or more likely to develop complications from A(H1N1) influenza, should be "the initial focus for immunization."
"They include pregnant women, household contacts of children under six months of age, healthcare workers and emergency medical services personnel, children and young people between the ages of six months and 24 years of age, and non-elderly adults with underlying medical conditions that increase their risk of complications from influenza," the CDC's Anne Schuchat told reporters.
But officials at the meeting also projected that only 120 million doses of the vaccine would be available by October.
And, Schuchat said, the vaccine would probably have to be administered in two doses.
But she played down the shortfall between the number of vaccine doses that would be available and the numbers earmarked for priority innoculation.
"With seasonal influenza, we recommend seasonal influenza vaccine to 80 percent of the country but we actually only reach around 40 percent of the people," she said.
"If we use seasonal influenza demand and uptake as our expectations, we may have plenty of vaccine right away."
Officials at the meeting also came up with a smaller target population, numbering about 41 million, who would be vaccinated before others if supplies of A(H1N1) vaccine are very limited, said Schuchat.
That smaller group would again include pregnant women and people who come into contact with children under six months, because very young infants cannot be vaccinated against flu; along with a subset of healthcare workers, children aged six months to four years of age, and children aged five to 18 with underlying health conditions, said Schuchat.
A study conducted by the CDC which was published Wednesday showed that pregnant women who fall ill with H1N1 influenza are more likely than the general population to develop serious complications and die, and recommended that they be given priority for vaccination against the virus.
Unlike seasonal flu, which usually hits elderly people the hardest, the A(H1N1) virus has mostly infected the young.