February 13, 2009

RSV study could point to new vaccination strategies

RSV study could point to new vaccination strategies

A new study by researchers at the Monroe Carell Jr. Children's Hospital at Vanderbilt indicates that the burden of respiratory syncytial virus (RSV) among young children is far higher than previously thought.

The study, published in The New England Journal of Medicine, estimates that each year 2.1 million children under age 5 require medical attention for RSV.

As part of the New Vaccine Surveillance Network, funded by the Centers for Disease Control and Prevention, Kathryn Edwards, M.D., and Marie Griffin, M.D., M.P.H., principal investigators for the study, and their research team collected samples from children younger than 5 who were admitted to Children's Hospital or seen in the Emergency Department or clinic with fever or respiratory symptoms.

Kathryn Edwards, M.D.

Kathryn Edwards, M.D.

Samples were also collected by a team from the University of Rochester School of Medicine and Dentistry in Rochester N.Y., and at Cincinnati Children's Hospital Medical Center.

Marie Griffin, M.D., M.P.H.

Marie Griffin, M.D., M.P.H.

They found that RSV was associated with 20 percent of hospitalizations, 18 percent of ED visits and 15 percent of office visits from November through April, which is peak season for the virus. Hospitalization rates for RSV were three times higher than those for influenza.

“The bottom line is that this is a very common respiratory virus in children,” Edwards said. “It has impact on children in all racial, gender and ethnic groups. It's an equal-opportunity infector.”

Almost all children will be infected with RSV by their second birthday, and it generally causes runny nose or congestion. It is also the cause of bronchiolitis, an inflammation of the smallest airway passages in the lungs. In the most severe cases, children may require ventilation, and a few children throughout the country die of the disease each year.
Edwards said these findings call for new vaccination strategies.

“We've focused for a long time on the most problematic children, the preemies and high-risk babies, but the largest number of children hospitalized with RSV are previously perfectly normal, healthy children. So our previous strategies that just target the high-risk population won't address the population with the highest burden, which is normal healthy babies.”

Researchers have been trying to develop a safe RSV vaccine for more than 30 years. There is currently an injected antibody available for high-risk children, but its expense prevents it from being a viable solution for the general public.

Edwards said researchers are working to develop a live weakened vaccine and to make the antibody cheaper.

“If we had a vaccine able to generate antibodies, it likely would have an enormous impact in all sectors,” she said.

This study reports on samples collected between 2000 and 2004, and investigators will continue to analyze data collected through 2008. Edwards is also working to secure funding to continue the surveillance.

The samples collected have been used in many other studies, from rhinovirus to asthma to influenza, and Edwards said they are a “treasure trove” that can shed light on the enormous impact of all viral diseases.

“We hope that these 10 years of work, which have really been a labor of love, will help us understand the patchwork of viral agents that cause disease,” she said. “We can then understand their impact more broadly.”