West Nile vaccine making progress
People inoculated with a vaccine being developed to protect against West Nile virus infection suffer no ill effects, and nearly all of them develop antibodies that neutralize the virus, researchers report.
“These are the first complete phase I results from a clinical trial of a West Nile virus vaccine,” Dr. Thomas Monath, Chief Scientific Officer for vaccine maker Acambis, told Reuters Health.
Results with the vaccine, called ChimeriVax-West Nile, were presented Wednesday at the National Foundation for Infectious Disease’s 8th annual vaccine meeting in Baltimore.
"Even at a very low dose, ChimeriVax-West Nile was extraordinarily effective,” Monath said
ChimeriVax-West Nile is a genetically engineered, live attenuated vaccine, Monath explained. “We actually took an existing vaccine against yellow fever, a related virus, and modified it for West Nile.”
For the trial, 30 healthy adult subjects were given a high dose of ChimeriVax-West Nile, 15 received a low dose, 30 received an inactive placebo injection, and 5 were given the yellow fever vaccine.
The percentage of subjects who developed high levels of neutralizing antibodies was 96 percent and 100 percent in the high- and low-dose groups, respectively.
No significant differences in the rates of treatment-related reactions were seen between the groups.
Given these encouraging results, a larger phase II trial is now in the works. Among other things, the goal will be to find the optimal dose, Monath noted. He estimated that if all goes well, ChimeriVax-West Nile could be on the market in three years.
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