By David Brown
Washington Post Staff Writer
Thursday, July 30, 2009
A complicated list of who should get pandemic flu vaccine in the fall is now set. When the vaccine starts arriving in September, first in line will be pregnant women; the caretakers of infants; children and young adults; older people with chronic illness; and health-care workers.
That's the advice of a 15-member committee of experts, which met all day Wednesday at the Centers for Disease Control and Prevention in Atlanta to advise the federal government on vaccine policy.
The priority list names targeted groups and suggests the order in which they should be vaccinated. While acknowledging the potential for confusion, the committee chose the strategy because of the possibility that the epidemic will be peaking within four to six weeks of when the vaccine becomes available.
"The results of this meeting will kick planning into high gear," said Pascale Wortley of the CDC's Immunization Services Division. "This is a watershed moment."
All that's missing is the vaccine, knowledge of how well it works and the nitty-gritty details of how to deliver it to people's arms and noses.
Manufacturers expect to deliver about 40 million doses of vaccine to the government and private distributors in September, and another 80 million doses in October. About 80 million doses a month will be delivered after that.
The vaccine will come in two forms: the traditional flu shot and a "live" vaccine squirted into the nose that contains a weakened version of the new virus.
Unlike nearly every previous effort to get people to use flu vaccine, the promotion of the pandemic vaccine won't first try to reach the elderly. That's because people 65 and older have contracted the new strain at the lowest rate of any age group and appear to be largely protected because of exposure to other distantly related flu strains that circulated decades ago.
The top-priority group includes about 160 million people and contains five populations: pregnant women; household contacts of children younger than 6 months; health-care and emergency medical services workers; everyone 6 months to 24 years old; and people 25 to 64 who have conditions that put them at higher risk of serious infection and death.
Only a fraction of each targeted group is expected to want the vaccine. Once the priority groups have been immunized, the vaccine can be offered to healthy adults ages 25 to 64, and after them, people 65 and older, the committee advised.
Health departments, clinics and private physicians will continue to urge the elderly to get the seasonal flu vaccine, which contains three strains circulating the world along with the new one.
The groups were selected because of long-standing knowledge of influenza outbreaks and the particular behavior of the new virus, which emerged in Mexico and Southern California in late April. Derived from two strains carried in pigs, the new influenza A (H1N1) virus was originally called swine flu.
Pregnant women account for about 6 percent of H1N1 deaths, as well as cases serious enough to require hospitalization, Anthony Fiore, a physician and epidemiologist at the CDC, told the Advisory Committee on Immunization Practices.
Children younger than 6 months do not produce a strong immune response to flu vaccine and are best protected by keeping them away from the virus, which is spread by coughing, sneezing and touching. Physicians, nurses and paramedics are high on the list because of the work they do.
In outbreaks during the spring, people ages 12 to 18 were hospitalized at twice the rate of people ages 19 to 24 and five times the rate of those 25 to 49. Of the 302 U.S. deaths recorded so far, more than half of those patients had an underlying chronic illness or medical condition such as asthma, diabetes, immune deficiency or morbid obesity.
In the "Asian flu" pandemic of 1957, which many experts believe is a model for the current one, many communities experienced an explosive spread of the virus once schools opened and the weather cooled.
Although CDC experts originally suggested making age 18 the ceiling of the healthy-young-people target group, the committee raised the age to 24 to include college students.
Some of the vaccine will be stored in multi-dose vials containing thimerosal, an antibacterial additive that contains mercury. But there will also be single-dose syringes without thimerosal, a substance that some assert is harmful to children.
Among the many unanswered questions is whether two doses will be necessary to provide full protection, how close in time two shots can be given and how big the dose will be. Vaccination programs may start before the answers are known.
Clinical trials in which the prototype vaccine will be tested in hundreds of children and adults are just beginning. Data on the effectiveness of one shot will be available in mid-September; two shots, in late September.