By Steven Reinberg
MONDAY, Sept. 21 (HealthDay News) -- Kids who are between 10 and 17 years old will apparently need only one shot of the H1N1 swine flu vaccine, according to initial results of ongoing trials, U.S. health officials announced Monday.
Children younger than 10 will probably need two doses of the new H1N1 vaccine, the officials added. That was expected because youngsters 6 months to 9 years of age typically need two doses of vaccine for the regular seasonal flu vaccine as well, because their immune systems are less developed.
"The initial results are encouraging," Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, said during a press conference. "As we had hoped, in children the 2009 H1N1 vaccine is acting just like the seasonal flu vaccine."
The preliminary results from the trials indicate that a single 15-microgram dose is well-tolerated and induces a robust immune response in most older children within eight to 10 days following vaccination, Fauci said.
Among children 10 to 17 years old, 76 percent had a "robust" immune response to the vaccine. For children 3 to 9 years old, 36 percent had a robust response. Among children 6 months to 36 months, the immune response rate was 25 percent, Fauci said.
Young children need two doses of flu vaccine -- whether for regular seasonal flu or H1N1 swine flu -- to prime their less-developed immune systems to develop antibodies to the flu, Fauci added.
Unlike regular seasonal flu, which typically strikes hardest at older adults, the H1N1 swine flu seems to target children and young adults, possibly because they may lack immunity to this strain of flu.
The officials reiterated that a seasonal flu shot won't protect you from the H1N1 flu, and an H1N1 shot won't protect you from the seasonal flu. So, children younger than 10 years of age will need four shots -- two seasonal flu shots and two H1N1 flu shots. Older children and adults will need just two shots -- one for seasonal flu and one for H1N1 flu.
"Overall, this is very good news for the vaccination program, both in regards to the supply of vaccine as well as to its potential efficacy," Fauci said.
The pediatric trial includes children 6 months to 17 years old and is testing responses to two doses of vaccine -- 15 micrograms and 30 micrograms, Fauci said. The vaccine is made by Sanofi Pasteur in Swiftwater, Pa.
U.S. health officials reported earlier that adults would need only one dose of the H1N1 flu vaccine.
On Friday, U.S. health officials said the first doses of the H1N1 swine flu vaccine will start shipping the first week in October, which is slightly earlier than expected. These first 3.4 million doses will come in the form of the nasal spray FluMist.
But FluMist is not recommended for children under 2 years of age; people with chronic medical conditions such as heart disease, kidney disease and diabetes; pregnant women; or people older than 49. Children, pregnant women, and people with chronic health conditions -- such as asthma, diabetes and heart disease -- are among those at greatest risk for complications from the H1N1 swine flu, according to the U.S. Centers for Disease Control and Prevention.
There may also be some injectable H1N1 flu vaccine available in early October, but how much is not known yet, officials said.
At a press briefing on Friday, Dr. Daniel Jernigan, deputy director of the Influenza Division at the CDC, said the H1N1 virus, though widespread, continues to produce mild illness in most people and recovery time is fairly quick.
Jernigan said it's important to get an H1N1 flu shot when the vaccine becomes available. People should also get a seasonal flu shot -- which is available now -- because the seasonal flu will start to circulate in the coming weeks, he said.
According to the CDC, those first in line for swine flu shots should be:
- Pregnant women.
- Children and young people from 6 months through 24 years of age.
- Health-care workers.
- Adults with chronic health conditions, such as asthma, diabetes and heart disease, or weakened immune systems, including cancer patients undergoing chemotherapy, organ-transplant recipients and people infected with HIV.
People who should get a seasonal flu shot include:
- Adults 50 and older.
- All children age 6 months to 18 years old.
- Pregnant women.
- People with chronic health problems like asthma, heart disease or a weakened immune system.
- Health-care workers.
- Caregivers of people at high-risk, including babies younger than 6 months of age.