The race to one of medicine’s elusive goals — a universal flu vaccine — is heating up. On Tuesday, the National Institutes of Health announced the phase I clinical trial of one such potential candidate, which will involve up to 100 adult volunteers. In early experiments, the vaccine appeared to protect animals exposed to fatal doses of multiple influenza strains.
The vaccine candidate is known as BPL-1357 and is being developed by researchers at the National Institute of Allergy and Infectious Diseases (NIAID). It contains four strains of avian influenza viruses that aren’t thought to be highly pathogenic, which are then further weakened and made unable to replicate.
In trials with both mice and ferrets, BPL-1357 suggested the tantalising promise of a universal buffer against the flu. Mice given BPL-1357 were able to survive lethal doses of six different flu strains, for instance, which included two subtypes that weren’t directly covered by the vaccine.
By contrast, our current seasonal flu vaccines can cover multiple strains, but have to be updated every year. They also tend to only provide modest protection against the flu, in part because the strains circulating in the world continue to evolve and don’t quite look like the strains selected to be in the vaccine months earlier. Another challenge is that they often don’t induce an immune response in the mucus-filled regions of our nose, throat and lungs, which is an important aspect of fighting off respiratory viruses like the flu.
Like the seasonal flu vaccine, BPL-1357 can be delivered as a nasal spray or intramuscularly with a shot. The vaccine’s trial will recruit volunteers between the ages of 18 to 55 and randomly sort them into three groups. One group will first receive a dose of BPL-1357 as a shot, then a saline placebo nasal spray; the other will receive a placebo shot, then the vaccine as a nasal spray; and the last will receive both a placebo shot and nasal spray. The groups will then be monitored and regularly undergo blood and nasal swab tests for about seven months.
Phase I trials are meant primarily to test the safety of a new drug or vaccine. But the samples collected from volunteers will allow researchers to get an early sense of whether BPL-1357 can induce a broad and durable immune response to the influenza virus in people. It may also show that one method of delivery is likely to be better than the other.
Vaccines given intranasally are typically better at inducing these kinds of mucosal immune responses. And if BPL-1357 can deliver on its potential, then it may not only protect us from the seasonal flu but future emerging strains passed down from birds and other animals that could threaten to become the next pandemic. That said, other universal flu vaccine candidates have crashed and burned over the years, so it will take time to tell whether BPL-1357 is the real deal. The trial is expected to be completed by early next year.
“Influenza vaccines that can provide long-lasting protection against a wide range of seasonal influenza viruses as well as those with pandemic potential would be invaluable public health tools,” said NIAID Director Anthony Fauci in a statement. “The scientific community is making progress on this pressing global health priority. The BPL-1357 candidate influenza vaccine being tested in this clinical trial performed very well in pre-clinical studies and we look forward to learning how it performs in people.”