The vaccine was less effective against the B strain (where a boost in titers was registered in more than 62 percent of participants) and H1N1 (where the boost was seen in more than 57 percent). The study included 221 people ages 18 to 49 who received either placebo or VLP vaccine.
"The success of this trial gives us the support that we need for Phase III," says Penny Heaton, Novavax's chief medical officer and vice president of development. "It's very encouraging." The company plans in October to conduct a separate test specifically to study the seasonal flu vaccine's effectiveness among 480 elderly participants (a demographic often encouraged to get seasonal flu shots), and Phase III efficacy trials across a larger set of demographics are scheduled to begin early next year.
Heaton thinks the success of Novavax's Phase II seasonal flu trial is encouraging for the company's efforts to also develop a vaccine for the H1N1 virus. Phase II trials for that vaccine candidate are set to begin within the next two months, so it will not likely be available to combat the current swine flu outbreak, which could kill as many as 90,000 Americans and land up to 1.8 million in the hospital, according to the President's Council of Advisors on Science and Technology (PCAST).
The advantage of Novavax's approach is that a vaccine can be made rapidly and in high volume, compared with the egg-based approach that's used today, says Ted Ross, an associate professor of microbiology and molecular genetics at the University of Pittsburgh's Center for Vaccine Research (CVR). "In the Novavax system, you generate a vaccine that looks just like the virus without being infectious," he adds.
This approach makes the FDA especially cautious. "Even though they're inactivating the virus, it's still there," says Ross, whose laboratory worked with Novavax during its preclinical studies, when the start-up was in need of laboratory facilities. Throughout the company's trials the FDA has been on alert for signs that a patient could have a bad reaction as a result of this vaccine-making approach.
Novavax is not the only company developing VLP-based vaccines, although it is ahead of the game in the category of flu vaccines. The only VLP-based vaccine to hit the U.S. market is Merck & Co.'s Gardasil, which won FDA approval in June as preventative against certain types of human papillomavirus (HPV), which could lead to cervical cancer. "This gave a huge boost to the VLP industry in that their vaccines could be approved," Ross says.
The current crop of seasonal flu vaccines, which contain H1N1, H3N2 and B flulike strains, are egg-based. "They're good, they're what we have," Novavax's Heaton says. "But there are improvements to flu vaccines that can be made that don't rely on our supply of eggs, and can do a better job for the elderly."