VCU to examine use of flu vaccines with young children

By Sathya Achia Abraham

RICHMOND, Va. (Sept. 29, 2004) – Virginia Commonwealth University researchers are studying an influenza vaccine administered by nasal spray versus injection to determine which method best protects against the illness in children aged 6 months up to 5 years.

The VCU School of Medicine’s Department of Pediatrics is one of about 300 sites around the United States expected to enroll a total of 7,000 children ages 6 months to 59 months in the phase III clinical trial. The trial next month is the final step in the study, which is examining the safety and efficacy of the nasal-spray vaccine for use in this population. The U.S. Food and Drug Administration in 2003 approved a nasal-spray vaccine for use in children 5 and older.

Linda D. Meloy, M.D., associate professor and interim chair of general pediatrics and emergency medicine, said new Centers for Disease Control and Prevention guidelines recommend that children 6 months to 23 months get the flu vaccine.

Influenza is responsible for about 36,000 deaths a year in the United States. The virus causes illness in all age groups, but rates of infection are highest in children, and a flu vaccination is the primary method to prevent illness.

“Children are the most susceptible to the flu virus,” Meloy said. “They can pick up the virus in day care or at school and bring it home where the virus can easily be transmitted to other family members.”

Meloy, who is the primary investigator of the study at VCU, said VCU hopes to enroll about 80 participants, and each child who participates will be immunized.

Most influenza vaccines contain a solution of live virus particles, but the concentration is so weak that it causes few, if any, symptoms in healthy people. The nasal-spray vaccine places the antibodies into the nose, where the flu virus first enters the system through inhalation. The injectable vaccine places the antibodies directly in the blood stream, so the virus must enter the system through the nose and travel into the bloodstream before the antibodies take effect. According to Meloy, if the antibodies are present in the nose, then the virus will immediately be subjected to the antibodies and possibly never enter the blood stream.

“The nasal-spray vaccine may offer better protection from influenza than the injectable vaccine because the virus is being attacked by the antibodies at an earlier stage of the viral process,” explained Meloy.

Each participant will be administered the nasal-spray and an injection — but only one of the methods will contain the flu vaccine. The participant will not be told which one is the vaccine. Researchers will follow-up with participants each week from the day the vaccination is administered, through to the peak of flu season, until May 2005. If a vaccinated child becomes ill with the flu, a researcher will take a swab of nasal secretion for further examination.

“Each year, the CDC determines which strains of the virus will likely cause an epidemic and tailors vaccines to those strains, which is why vaccine supplies are not available until October,” said Meloy. “The flu virus changes every year and new vaccines must be made in order to protect against the new strain of the virus.” The strains for the 2004-2005 seasons are: A/New Caledonia, and A/Fujian vaccine and B/Shanghai.