An experimental vaccine against respiratory syncytial virus (RSV), one of the leading causes of infectious disease deaths in infants, has shown early promise in a Phase 1 human clinical trial.

A team of researchers report in the journal Science that one dose of their vaccine candidate elicited large increases in RSV-neutralizing antibodies that were sustained for several months.

People contract RSV in all stages of life, but it’s most dangerous in the very young and the very old. The virus causes pneumonia, bronchiolitis and other lower respiratory tract diseases. Every year, millions of people become sickened by RSV, and more than 100,000 die, mostly in areas that lack access to modern medical care. For infants under 1 year of age, RSV is second only to malaria for infectious disease deaths.

Barney Graham and Peter Kwong of the National Institute of Allergy and Infectious Diseases’ Vaccine Research Center (VRC), along with The University of Texas at Austin’s Jason McLellan, a former postdoctoral researcher at VRC and now an associate professor at UT Austin, spearheaded the development of the vaccine candidate DS-Cav1.

The Science report is an interim analysis of data from the first 40 healthy adult volunteers enrolled in the trial, which began in the National Institutes of Health Clinical Center in 2017. Researchers found that the vaccine candidate elicits a greater than 10-fold increase in RSV-neutralizing antibodies, compared with the number of antibodies a person produces naturally from RSV exposure earlier in life.

Many drugs fail to make it all the way through clinical trials. But if this one does, or another based on the same F protein structure that he helped discover, McLellan says it could be a game changer. “If it works reasonably well and we prevent 70 to 80 percent of all deaths, just think of all the little infants and toddlers we’d save,” McLellan said. “There aren’t that many vaccines in the world, and so if we’re able to actually participate in making one that works and saves lives, that would be awesome.”