Promising Trials for More Affordable Japanese Encephalitis Vaccine

Stock image of a mosquito on human skin. (lksuperboy/Pixabay)

Researchers in Queensland are trialling a new alternative to the delivery of the Japanese encephalitis (JE) vaccine by injecting the inoculation into the top layer of the skin to increase affordability and take-up numbers in Australia.

“This potential approach could lower the cost of JE vaccination and protect four times as many people per vaccine vial,” Dr Luis Furuya-Kanamori from The University of Queensland (UQ) said.

Though the research is currently in its preliminary phase, Furuya-Kanamori said the initial results of an effective vaccine despite reduced dosage are encouraging.

“Participants were given a micro-dose of an existing vaccine into the top layer of the skin rather than in the deeper layers,” he said.

“After eight weeks, the first 11 participants had all produced good antibody levels without severe adverse events.”

Japanese encephalitis is a potentially deadly arbovirus transmitted by mosquitos that cause high levels of human disease.

Studies have shown that the virus not only kills brain cells but also prevents the recovery of brain tissue by inhibiting the birth of new neurons.

Those infected show symptoms of fever and headache and people with severe infection may experience neck stiffness, disorientation, tremors, coma and seizures.

Whilst less than one percent of individuals infected will show symptoms of disease, only around one-third of diseased individuals will fully recover from the virus.

Currently, treatment for JE is very limited, though the disease is preventable through a vaccine.

“We first started this research looking for a way to increase the rate of vaccination among Australians travelling to countries and areas with the virus,” Furuya-Kanamori said.

“While there are widely-used and effective JE vaccines available in Australia, the problem is they cost about $300 for travellers, so many people simply don’t get vaccinated.”

The news of this research comes timely as cases of JE are detected in four states across Australia with the disease being declared a national significance on March 4.

UQ is currently seeking volunteers to trial the effectiveness of vaccinating individuals with the traditional, registered Australian JE vaccine but in a micro-dose and delivered to the top layer of the skin to see if using a lower dose in this way makes the vaccine cheaper and less painful for the recipients.

Influenza studies have shown that intradermal injections have a dose-sparing effect; where less dosage is required for the same level of protection.

However, traditionally, vaccines are delivered intramuscularly or intravenously, with only very few vaccines such as yellow fever and rabies approved to be injected into the top layer of the skin.

Associate Professor Greg Devine from the Queensland Institute of Medical Research said that “as the trial proceeds, we’ll determine whether the micro-dose consistently produces the required antibody levels across a much larger group of people.”

“Our preliminary results reflect similar findings for the low dose intradermal administration of other vaccines including Yellow Fever and rabies vaccines.”