Doctors in Halifax are testing a new vaccine that could protect children against a widespread — and potentially deadly —  respiratory infection.

Respiratory syncytial virus (RSV) is a common virus almost all children are infected with by the time they’re three years old, according to the Canadian Lung Association.

In most cases it amounts to little more than a cold, but some children are hospitalized or worse. Around 200,000 children die from the virus each year, mainly in developing countries.

“If this vaccine is safe and effective, it would have great promise for reducing the amount of illness and death that occurs around the world for young children with RSV,” said Dr. Joanne Langley, who is leading the clinical trials.

“This is an exciting time for RSV vaccine research because there's been a number of potential vaccines that are promising.”

The vaccine was developed by GlaxoSmithKline Inc., but is being tested by the Canadian Center for Vaccinology in Nova Scotia.

The goal is to be able to vaccinate pregnant women, which will in turn immunize unborn children.

The first set of human trials is being conducted on men, like Dalhousie University economics student Marc Gordon.

He said he hopes he can play a role towards diminishing the virus’s toll.

“Ultimately a vaccine that's available for mothers and new children everywhere,” he said.

If the vaccine proves safe, women will be tested next, then pregnant women, then a randomized trial.

Researchers said the trials will take about five years.

There is already a drug that helps prevent RSV on the market, but palivizumab needs to be injected five times over the winter season. It's also very expensive.

Between 66,000 and 199,000 children under the age of five died of RSV in 2005, according to a 2010 World Health Organization study funded by the Bill & Melinda Gates Foundation.

Around 99 per cent of those deaths were in developing countries.