Respiratory Syncytial Virus Vaccine Begins Clinical Testing

A phase 1 clinical trial of a respiratory syncytial virus (RSV) candidate vaccine, DS-Cav1, recently began to evaluate the safety and tolerability of the vaccine.

The investigators will also be assessing the vaccine’s ability to elicit an immune response in healthy adults, according to a press release from the National Institutes of Health (NIH). The candidate was created by researchers at the National Institute of Allergy and Infectious Disease.

A majority of individuals have been exposed to RSV by age 2, and they typically experience repeated infections. Typically, the infection presents as mild, cold-like symptoms that resolve in a matter or 1 to 2 weeks.

However, RSV poses a threat to children younger than 2 with heart or lung problems, premature infants, children and adults with weak immune systems, and the elderly, according to the NIH. These populations can experience severe lower respiratory tract diseases, such as pneumonia and bronchiolitis.

Approximately 2% of infants under 1-years-old require hospitalization related to RSV, while children aged 1 to 5 and those older than 65-years-old are at high risk of being hospitalized from the infection, the NIH reported.

The CDC estimates that RSV causes 57,527 hospitalizations and 2.1 million outpatient visits among individuals younger than age 5, and 14,000 deaths among the elderly in the United States each year. Worldwide, the infection is estimated to cause more than 250,000 deaths annually.

There is currently no vaccine available to prevent the infection, nor are there drugs available to treat it. Palivizumab, a monoclonal antibody, was approved by the FDA to prevent lower respiratory tract disease related to RSV among high-risk children, but is not available to treat other patient groups, according to the press release.

“RSV is underappreciated as a major cause of illness and death, not only in infants and children but also in people with weakened immune systems and the elderly,” said NIAID Director Anthony S. Fauci, MD. “A vaccine to reduce the burden of this important disease is badly needed.”

The VRC317 clinical trial will enroll healthy adults from age 18 to 50 who will be randomized to receive 2 injections 12 weeks apart with DS-Cav1 or the candidate vaccine plus alum. Alum is used in vaccines to improve the body’s immune response, according to the press release.

Patients will also be randomized to receive varied doses of DS-Cav1 — 50 mcg, 150 mcg, or 500 mcg. The investigators plan to vaccinate 5 individuals with the lowest dose, and work their way up to the highest dose if patients do not experience serious adverse reactions.

After 44 weeks from the initial injection, patients will return for 12 visits where clinicians will conduct physical exams and collect blood samples, the NIH reported. Mucous samples from the mouths and noses of participants will also be collected to measure immune response.

The investigational vaccine is a structurally-engineered protein from the surface of RSV instead of being based on an inactive virus. The vaccine was previously observed to protect against the virus in mice and nonhuman primates, and moved into clinical trials.

“This work represents an example of how new biological insights from basic research can lead to candidate vaccines for diseases of public health importance, and the value of multidisciplinary research teams like the ones assembled at the VRC,” concluded Barney S. Graham, MD, PhD, deputy director of the NIAID’s Vaccine Research Center.