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Swine Flu Vaccine Protects Pregnant Women

1 Dose of H1N1 Vaccine Works for Pregnant Women; Kids Still Need 2 Doses
WebMD Health News
Reviewed by Louise Chang, MD

Nov. 2, 2009 - Pregnant women safely get "robust" protection from one dose of the H1N1 swine flu vaccine; but children under age 10 really need two doses, NIH studies show.

The findings are straight-from-the-clinic data from ongoing studies funded and coordinated by the National Institute of Allergy and Infectious Diseases (NIAID) at clinical centers across the country.

"This should be reassuring news to those women who already have received the H1N1 vaccine, and it is vital information for those pregnant women who have not been vaccinated," NIAID Director Anthony Fauci, MD, said at a news conference. "Importantly, the pregnant women participating in the trial have tolerated the vaccine well and no safety concerns have arisen."

As the current wave of the H1N1 swine flu pandemic sweeps the nation, it's becoming clear that pregnant women -- especially those in their second and third trimesters -- bear a special risk. They are about six times more likely than other healthy adults to develop severe complications soon after infection with H1N1 swine flu.

Alarmingly, a recent CDC survey found that about half of pregnant women and other adults with risk conditions do not seek medical attention when they come down with H1N1 swine flu symptoms.

It's also becoming increasingly clear that H1N1 swine flu is mainly a disease of young people. Children, teens, and young adults bear the brunt of infections -- and of hospitalizations and deaths.

The NIAID clinical trials have shown that children, teens, and young adults over age 10 need just one dose of the H1N1 swine flu vaccine for protection.

Early results from these studies suggested younger children might need two doses. That's true, new study results show.

Even three weeks after getting their first dose of H1N1 swine flu vaccine, only 25% of kids ages 6 to 35 months and only 55% of kids ages 3 to 9 years are protected. Even giving these kids a one-time double dose did not improve immune responses.

The good news: Just eight to 10 days after getting their second dose of the vaccine -- four weeks after the first dose -- virtually every kid in these age groups has a protective immune response.

"These data support guidelines that recommend two vaccine doses for younger children," Fauci said.

H1N1 Swine Flu Vaccine Safety

Bruce Gellin, MD, head of the government's National Vaccine Program Office, said at the news conference that a group of medical experts will this week begin regular meetings to analyze safety data on the H1N1 swine flu vaccine.

The group is part of a larger panel, the National Vaccine Advisory Committee, that advises Health and Human Services Secretary Kathleen Sebelius on vaccination issues. It was this group that previously advised the government to release H1N1 vaccine as soon as it became available.

Gellin also announced the release of a detailed plan to monitor the safety of the 2009 H1N1 swine flu vaccine. The plan has 11 elements:

  1. Analysis of background rates of rare adverse events that occur without vaccination, to make it easier to determine whether vaccination increases the rate at which any of these events occurs.
  2. Use of the CDC's Vaccine Safety Datalink system, which links data from eight managed-care organizations with data on 9 million Americans -- 3% of the U.S. population.
  3. Use of the Medicare/Medicaid database.
  4. The Post-Licensure Rapid Immunization Safety Monitoring (PRISM) system, which links data from large insurance plans covering about 10% of the U.S. population.
  5. Use of the Department of Defense medical databases.
  6. Use of the Veterans Affairs databases.
  7. A surveillance program to look specifically for cases of Guillain-Barre syndrome (GBS), a rare neurological condition.
  8. A collaboration between Johns Hopkins University and the CDC in which people who received the H1N1 swine flu vaccine report their experiences via the Internet.
  9. Use of electronic records that will be introduced by the Indian Health Service.
  10. The Clinical Immunization Safety Assessment (CISA), a collaboration between six academic centers that will collect and store clinical samples from people who may be at risk for serious adverse events linked to vaccination or influenza.
  11. The Vaccines and Medications in Pregnancy Surveillance System (VAMPSS), a collaboration between an association of birth-defect specialists, the American Academy of Allergy, Asthma, and Immunology, and Boston University, which will conduct studies of H1N1 swine flu vaccine, H1N1 swine flu antiviral treatment, and H1N1 swine flu disease.

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