Respiratory Infection Vaccine Shows Promise

Respiratory syncytial virus vaccine candidate found effective in early trials

(RxWiki News) Respiratory syncytial virus (RSV) is a common and highly contagious virus that can be especially dangerous for babies. But the virus may have finally met its match.

Researchers from Johns Hopkins Bloomberg School of Public Health (JHSPH) have developed a promising new candidate vaccine for RSV. So far, the experimental vaccine is working as hoped, researchers said.

According to the Centers for Disease Control and Prevention (CDC), RSV is the most common cause of bronchiolitis (inflammation of the small airways in the lungs) and pneumonia in US children younger than 1. RSV is also responsible for up to 200,000 deaths worldwide each year.

RSV infects the lungs and breathing passages. Healthy adults and older children typically only experience mild, cold-like symptoms and recover within a week or two. However, this virus can cause serious, life-threatening complications in babies and the elderly. No vaccine currently exists to protect against RSV.

The candidate vaccine is created using a weakened version of the live RSV virus. This method is similar to vaccines used to prevent measles, mumps and rubella.

Creating a vaccine this way, however, requires a delicate balance: The virus must be weak enough not to cause illness and strong enough to cause an immune system response.

The vaccine, called MEDI ΔM2-2, was created from a genetically engineered version of the virus that is missing the M2-2 protein gene. According to the authors of this study, M2-2 acts like a switch — when it's deleted, the virus produces more viral proteins that trigger immune response but fewer that cause illness.

For this study, a team of researchers led by Ruth A. Karron, MD, tested the new vaccine on adults and older children who had previously been infected with RSV. The vaccine was also tested on infants and younger children who had not been exposed to the virus. The vaccine was administered nasally.

These researchers found that the vaccine produced more RSV antibodies in young children when compared to a prior vaccine candidate.

Some vaccinated children also had strong immune system responses when they encountered RSV in the community and did not develop illness that required medical attention as a result.

"These early clinical data are exciting, and make us think differently about the development of live vaccines for RSV," Dr. Karron, a professor of international health at JHSPH, said in a press release. "If this research is borne out in future studies, we could be less than a decade away from a safe and effective live-attenuated vaccine for RSV."

This study was published Nov. 4 in the journal Science Translational Medicine.

The National Institute of Allergy and Infectious Diseases and the National Institutes of Health funded this research. Dr. Karron and team disclosed no conflicts of interest.

Review Date: 
November 4, 2015