Researchers claimed to have successfully completed the first human trial of a vaccine for a common virus that is particularly dangerous to infants.

After fifty years of failed attempts around the world, a vaccine for respiratory syncytial virus (RSV), may now be within sight.

The vaccine, developed and initially tested by biotechnology firm Reithera, may help in preventing a leading cause of serious illness in babies, reports the BBC.

The latest vaccine uses genetic engineering to trick the immune system into thinking that it is dealing with RSV.

It is said that the 'viral vector' technology is the similar to one used in the new Ebola vaccines. It contains a harmless virus that cannot cause illness, and which has been modified to produce some RSV proteins on its surface, the journal Science Translational Medicine reports.

Each year RSV kills around 200,000 people worldwide, affecting those most with compromised immune systems - including young infants and the elderly.

RSV also affects two-thirds of babies in their first year and is second only to malaria as a killer of children under one in developing world.

To come to this conclusion, researchers from the Oxford Vaccine Group tested two candidates - one using a chimpanzee cold virus never before used in humans and the other a harmless pox virus - in 42 adult volunteers.

They found both components of the vaccine to be safe and produced an immune response.

While the results are encouraging, this was just the first stage in many years of trials.

Dr Christopher Green, the lead physician for the trial and a clinical research fellow at Oxford University said, "What was particularly exciting about the viral vector technology used in their trials was that similar vaccines, including ones for malaria, had already been successfully used in infants.

"This is encouraging data, he said. "The results of this trial are a positive signal that prevention of RSV is achievable."

The team will embark on tests of another vaccine using the same technology that is being specifically designed for use in children.