A single dose of a breathable, respiratory vaccine may provide long-term protection against the deadly Ebola virus, scientists say.

Results from a recent pre-clinical have shown that a single dose of a non-injectable vaccine provided long-term protection for non-human primates against the Ebola virus.

A breathable vaccine could surmount the logistical obstacles of storing, transporting and administering injectable vaccines in parts of Africa most afflicted by the virus, researchers said.

The current Ebola outbreak in Western Africa, which has killed almost 5,000 people, is the largest and most complex epidemic since the virus was first discovered in 1976, according to the World Health Organisation.

Researchers in the new study have worked over seven years to develop a respiratory formulation that improved survival of immunised non-human primates from 67 per cent to 100 per cent after challenge with 1,000 plaque forming units of Ebola Zaire 150 days after immunisation.

This improvement is statistically significant because only 50 per cent of the primates given the vaccine by the standard method of intramuscular injection survived challenge, researchers said.

Ebola causes devastating outbreaks with fatality rates of 25 to 90 per cent in Africa and Asia. Although progress has been made in understanding the virus’ biology, no licensed vaccines or treatments currently exist, noted the researchers.

“The main advantage of our vaccine platform over the others in clinical testing is the long-lasting protection after a single inhaled dose,” said Professor Maria Croyle of The University of Texas at Austin’s College of Pharmacy, a co-author of the paper.

“This is important since the longevity of other vaccines for Ebola that are currently being evaluated is not fully evaluated.

“Moreover, this immunisation method is more attractive than an injectable vaccine given the costs associated with syringe distribution and needle safety and disposal,” Croyle said.

The next stage of research for Croyle and colleagues is a phase I clinical trial that tests the effectiveness of their vaccine in human subjects.

They will also further explore preliminary data they have collected for administration of the vaccine as a thin film under the tongue in non-human primates.

Related Topics