MedImmune announces interim data from its live attenuated influenza vaccine studies

Oct 23 2009

MedImmune announced today that interim data from human studies of its nasal spray vaccine for the 2009 novel Influenza A (H1N1) virus demonstrate a similar clinical profile in children and adults 2 to 49 years of age as previously studied seasonal formulations of the vaccine. The live attenuated influenza vaccine (LAIV) for the 2009 novel Influenza A (H1N1) virus received approval from the U.S. Food and Drug Administration (FDA) on September 15, 2009.

"MedImmune is pleased to report these findings that demonstrate that the safety profile and immunogenicity of our nasal spray vaccine for the 2009 H1N1 virus is, as expected, similar to our seasonal influenza vaccine," said Filip Dubovsky, M.D., vice president, clinical development, vaccines. "It is rewarding for all of us at MedImmune to see the vaccine being used to help protect the U.S. population from this novel strain of influenza."

Two randomized, double-blind, placebo-controlled trials are ongoing in children (2-17 years) and adults (18-49 years) to evaluate the safety, tolerability, and immunogenicity of vaccine. A total of 326 children and 300 adults were randomly assigned to receive 2 doses of 2009 H1N1 LAIV or placebo 28 days apart. Both clinical trials are collecting data following a second dose of the vaccine.

LAIV for 2009 H1N1 is made using the same process as LAIV for seasonal influenza. The safety of the 2009 H1N1 vaccine was evaluated in the same way that the safety of new seasonal LAIV strains is assessed every year. The H1N1 vaccine was also evaluated in children to further establish its safety profile.

In children, the most common side effects following the first dose of vaccine included headache, runny/stuffy nose, and cough. In adults, the most common side effects were headache, runny nose and decreased activity. Symptoms after the second dose were similar but generally occurred at lower rates in both children and adults. No vaccine-related serious adverse events have been reported in children or adults. The local and systemic symptoms observed are consistent with intranasal vaccine virus replication and are similar to those observed with seasonal LAIV. Serum antibody responses to the vaccine in addition to pre-clinical characterization data are also consistent with previously studied formulations of seasonal LAIV, which has been shown in multiple studies to be safe and effective in eligible children and adults 2 to 49 years of age.

LAIV initiates the immune response in the nose, where the virus enters the body and replicates, and is the key to establishing a vaccine response that will help prevent disease if the person later encounters a circulating H1N1 virus. In response to the vaccine, the body develops mucosal immunoglobulin A (IgA), serum immunoglobulin G (IgG), and cellular immunity to help protect the individual from infection from an influenza virus.

Study results have been submitted to and reviewed by authorities at the FDA, the U.S. Centers for Disease Control and Prevention (CDC), the National Institutes of Health (NIH), and the U.S. Department of Health and Human Services (HHS).