No Loss of Efficacy When H1N1, Seasonal Flu Vaccines Given Simultaneously
By Robert Lowes
Medscape Medical News
October 12, 2009 — Injecting patients with the H1N1 flu vaccine in one arm and the seasonal flu vaccine in the other does not impair the effectiveness of either in producing an immune response, according to early data from a trial sponsored by the National Institute of Allergy and Infectious Diseases (NIAID).
"That will be important as we roll out the vaccination program and individuals...go to their [physician's] offices and would like to get those vaccinations at the same time," said NIAID Director Anthony Fauci, MD, at a Friday press conference. Administering the vaccines together also is not leading to greater adverse effects, said Dr. Fauci.
Previously, the US Centers for Disease Control and Prevention had advised clinicians that they could administer inactivated versions of both the seasonal flu vaccine and the H1N1 vaccine during the same patient visit, or any time before or after each other. Preliminary results from the trial confirm the recommendation for vaccine coadministration as one of several options, NIAID stated in a bulletin.
The trial is not assessing immune response to nasal-spray vaccines that contain a live, but weakened virus. A company called MedImmune makes such vaccines for both the H1NI and seasonal flu viruses. For comprehensive guidance on administering combinations of the inactivated vaccines and their nasal-spray counterparts for both strains of influenza, visit the "H1N1 Clinicians Questions and Answers" page of the CDC Web site, the NIAID release states.
2 Doses of H1N1 Vaccine Do Not Substantially Increase Immunity
Ongoing findings from the NIAID-sponsored trial also suggest that 2 sequential doses of the H1N1 virus do not confer greater immunity than 1 dose, Dr. Fauci said.
The trial initially indicated that within 8 to 10 days, a single, 15-μg dose of unadjuvanted, inactivated viral material triggered an effective immune response in healthy adults as well as the elderly. Patients in the trial also received a second dose 21 days after the first one. However, 8 to 10 days after the second dose, the immune response was not substantially greater than that seen at 21 days after the first dose, said Dr. Fauci.
"That just confirms the concept that a single dose of 15 μg of unadjuvanted material is sufficient to induce a robust response that you would be predict would be protective," he said.
The full text of the news release is available on the NIAID Web site.