News Release

Thursday, December 10, 2009

NIAID Trial of 2009 H1N1 Influenza Vaccine Enrolling HIV-Positive Adults

Trial Complements Current Studies in HIV-Infected Children and Pregnant Women.

HIV-infected adults currently are being recruited to participate in a clinical trial of 2009 H1N1 influenza vaccine. The study, sponsored by the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health, will enroll approximately 240 men and women between the ages of 18 and 64.

"People with suppressed immunity caused by conditions such as HIV infection are at increased risk of serious illness from 2009 H1N1 influenza, and should be vaccinated against the H1N1 virus," says NIAID Director Anthony S. Fauci, M.D.

"However, such immune suppression may hamper the response to influenza vaccines,” Dr. Fauci adds. "While people with HIV infection are a high-priority group to receive 2009 H1N1 influenza vaccine, the optimal dosage of 2009 H1N1 vaccine for people with HIV infection has not been determined through clinical trials. This study will help address that gap in knowledge."

All study participants will receive two doses of an inactivated 2009 H1N1 influenza vaccine, administered approximately 21 days apart. The vaccine is manufactured by Novartis. Half of the volunteers will receive two 15-microgram doses and the other half two 30-microgram doses of the vaccine.

Within each dosage group, volunteers will be further divided into two groups based on their CD4+ T-cell levels. CD4+ T cells are infection-fighting white blood cells that are targeted by HIV. Healthy people usually have between 800 and 1,200 CD4+ T cells per milliliter of blood. Over time, most people with HIV show a drop in CD4+ T-cell counts, though antiretroviral therapy can help restore them to healthy levels.

For each dosage group (15 micrograms and 30 micrograms), the investigators are seeking 60 volunteers who have CD4+ T-cell counts below 200, and 60 who have CD4+ T-cell counts equal to or greater than 200. The new study will analyze how CD4+ T-cell levels affect the response to the vaccine.

The trial is being conducted at six sites, including these five NIAID-funded Vaccine and Treatment Evaluation Units: Baylor College of Medicine, Houston; Cincinnati Children’s Hospital Medical Center; Saint Louis University, Mo.; University of Iowa, Iowa City; and University of Maryland, Baltimore. The University of Washington, Seattle, also is participating in the trial.

Additional details about this study are available at

The new study is the third NIAID-sponsored trial of 2009 H1N1 influenza vaccine in people with HIV infection. The earlier trials began in October and enrolled HIV-infected pregnant women and children and young adults with HIV. For more information about those trials, see:

Visit for one-stop access to U.S. government information on pandemic flu. Also, visit NIAID's flu Web portal

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