Very low doses of Novavax Inc.’s pandemic influenza vaccine provided protection against a lethal challenge of live H5N1 viruses, according to pre-clinical data presented here today at the Second International Conference on Avian Influenza in Humans.
The data show that two 0.6 microgram doses of Novavax’s virus-like particle (VLP) H5N1 vaccine — without the addition of an adjuvant — protected ferrets from challenges with live H5N1 bird flu viruses.
This dose is 25 fold lower than the average human dose for most seasonal flu vaccines and more than 100 times lower than other H5N1 vaccines against avian influenza. Novavax plans to submit an investigational new drug application to the U.S. Food and Drug Administration in mid-2007 to commence human clinical trials with the novel H5N1 influenza vaccine.
“We are extremely encouraged that even very low doses of our vaccine are proving to be effective in pre-clinical models without the need for adjuvants,” said Dr. Rick Bright, Novavax’s Vice President of Global Influenza Programs. “This may be important in a pandemic, where the vaccine supply could possibly need to be ‘stretched’ to meet the significant global demand.”
In the study, ferrets were inoculated with a range of doses of the company’s VLP vaccine made from an Indonesian strain of H5N1 avian influenza. The ferrets, which represent the most relevant influenza animal model for humans, were then challenged with live H5N1 virus, and all survived. The typical human dose of a seasonal influenza vaccine is 15 micrograms. Other pandemic vaccines with no adjuvant have shown only modest levels of immunogenicity in humans with doses as high as 90 micrograms. In this study, ferrets received either 15, 3 or 0.6 micrograms of Novavax’s vaccine, and all immunized animals had similar survival results.
In addition, ferrets were protected not only against the Indonesian strain of avian flu but were cross-protected against a separate challenge strain originating in Vietnam. Again, all ferrets that received the Novavax vaccine survived, even those that received the lowest 0.6 microgram dose.
The International Conference on Avian Influenza in Humans brings together leading bird flu experts at the Pasteur Institute to review and discuss the latest scientific advances in vaccine prevention strategies and treatments designed to stem a pandemic.
The U.S. Centers for Disease Control and Prevention currently is testing antibodies from these animals against a number of additional strains of H5N1 that have been detected in recent years to establish whether the vaccine is even more broadly cross-protective.