Nasal Flu Vaccine More Effective in Children (I)

by BETH M. WICKLUND, M.D.

Young children and their parents may soon have less of a reason to cry when going to the doctor.

A nasal spray vaccine for the flu virus has been shown to be more effective in children than the standard intramuscular needle injection currently being used.

Content
New Mammogram Guidelines | Ask Dr. TimIn a study of nearly 8,000 children released today in the New England Journal of Medicine, children younger than 5 years old who received the nasal vaccine developed 55 percent fewer cases of the flu than those who received the injected vaccine.

"This vaccine will eventually lead to an easier process of vaccination and will substantially change the way pediatricians vaccinate children against the flu," said Dr. Robert Belshe, lead author of the study and director of the Center for Vaccine Development at Saint Louis University Health Sciences Center.

Not only did the nasal spray beat out the injectable vaccine against the strains of influenza actually contained in the vaccines, but it also prevented more infections caused by strains that were genetically drifted, or different, from the vaccine strains.


"It's as though you get a double-bang effect," said Dr. William Schaffner, chair of the department of preventive medicine at the Vanderbilt Medical School in Nashville, Tenn.

"You get protection against the kind of influenza that is in the vaccine, as well as the kind that sometimes occurs out in the community and is a little bit different," Schaffner said.

Should all children now start to receive the nasal vaccine? There are precautions. Children who are 6 months to 1 year of age were almost twice as likely to develop wheezing and other illnesses within six weeks of their immunization if they received the nasal vaccine rather than the injected one.

In addition, all children with a history of wheezing or asthma -- even older children -- were slightly more likely to be hospitalized if they were given the nasal vaccine.

The reason for the rise in other illnesses is unclear, but it is concerning enough that Belshe says, "The nasal spray vaccine should become the vaccine of choice for children over 1 year of age without a history of wheezing [or asthma]. It is easier to use and has greater efficacy."

Flu vaccines are still very important for infants between 6 months and 1 year, and the injected vaccine should continue to be used.

Dr. Kathleen Neuzil, chair of the Pandemic Influenza Task Force of the Infectious Disease Society of America, said, "If the nasal vaccine causes some side effects, then we need to weigh the risks and benefits in each patient."

Future studies may investigate a combination of the injected and nasal vaccines in an effort to balance efficacy and safety in children younger than 1 year old.

The nasal vaccine contains virus that is still alive but disabled, so it doesn't cause the flu itself. In children, the live virus multiplies in the body and causes a stronger immune response than the injectable vaccine, which contains only inactivated virus particles.

This form of the vaccine is not as effective in adults, whose more mature immune systems do not allow the virus to replicate as much.

FDA approves seasons influenza vaccines

The U.S. Food and Drug Administration (FDA) today announced that it has approved this year's seasonal influenza vaccines that include new strains of the virus likely to cause flu in the United States during the 2008-2009 season.
The six vaccines and their manufacturers are: CSL Limited, Afluria; GlaxoSmithKline Biologicals, Fluarix; ID Biomedical Corporation of Quebec, FluLaval; MedImmune Vaccines Inc., FluMist; Novartis Vaccines and Diagnostics Limited, Fluvirin; and Sanofi Pasteur Inc., Fluzone.

Approval information and specific indications can be found at http://www.fda.gov/cber/flu/flu2008.htm.

This season's vaccines contain three strains of the influenza virus that disease experts expect to be the most likely cause of the flu in the United States.

Each season's vaccines are modified to reflect the virus strains most likely to be circulating. The closer the match between the circulating strains and the strains in the vaccines, the better the protection.

There is always a possibility of a less than optimal match between the virus strains predicted to circulate and what virus strains end up causing the most illness. Even if the vaccines and the circulating strains are not an exact match, they will provide some protection and may reduce the severity of the illness or prevent flu-related complications.

"One of the biggest challenges in the fight against influenza is producing new vaccines every year," said Jesse L. Goodman, M.D., M.P.H., director of FDA's Center for Biologics Evaluation and Research. "There is no other instance where new vaccines must be made every year. The approval of flu vaccines is a part of FDA's mission to promote the health of Americans throughout the year."

The FDA changed all three strains for this year's influenza vaccine-an unusual occurrence, as usually only one or two strains are updated from year to year. A list of the strains included in the 2008-2009 vaccine can be found at http://www.fda.gov/cber/flu/flu2008.htm. Of note, two of the three strains recommended for the U.S. this year are now in use for the Southern Hemisphere's 2008 influenza season, which is currently underway.

Each year, experts from the FDA, World Health Organization, U.S. Centers for Disease Control and Prevention (CDC), and other institutions study virus samples and patterns collected throughout the year from around the world in an effort to identify strains that may cause the most illness in the upcoming season.

Based on those forecasts and on the recommendations of its Advisory Committee, the FDA each February decides on the three strains that manufacturers should include in their vaccines for the U.S. population. The FDA makes this decision early in the year so that manufacturers have enough time to produce the new vaccines.

Vaccination remains the cornerstone of preventing influenza, a contagious respiratory illness caused by influenza viruses. According to the CDC, every year an average of 5 to 20 percent of the U.S. population gets the flu, more than 200,000 are hospitalized from flu complications and there are about 36,000 flu-related deaths. Some individuals - the elderly, young children, and people with chronic medical conditions - are at higher risk for flu-related complications. Vaccination of these groups and of health care personnel is critical.

"Currently, only 40 percent of health care workers in the United States are vaccinated against influenza," said Department of Health and Human Services' Assistant Secretary of Health Joxel Garcia, M.D., M.B.A.

"Increasing the number of vaccinated health care personnel can be a strong front in the annual battle against the flu," said Garcia. "Health care workers can set an example for the patients they serve as well as decrease the likelihood of contracting and transmitting the virus."

http://www.fda.gov