Pandemic re-emphasizes need for universal flu vaccine
The quest for a universal flu vaccine in the U.S. is making "promising" progress, with the possibility of having one ready in five years.
Why it matters: Just because we're battling a coronavirus pandemic right now, doesn't mean a deadly influenza pandemic isn't waiting around the corner. Experts are aiming to create a vaccine that could target a broader array of flu strains in order to prepare for future pandemics.
"The universal flu vaccine is probably one of the most sought-after infectious disease countermeasures, because influenza has caused such a huge burden of infection every year and is very disruptive. ... And, most of our pandemic virus threats come from the influenza virus family."— Amesh Adalja, senior scholar, Johns Hopkins Center for Health Security
Background: Currently, seasonal flu vaccines (and some treatments) are the only options available to combat influenza, which has multiple strains that can mutate quickly, killing tens of thousands of Americans every year.
- "They're not perfect. And, in fact, they could be a lot better," says John Mascola, director of the NIH's Vaccine Research Center (VRC).
- Because the current main method of producing these vaccines requires decisions about which strains to target to be made roughly six months prior to the season's start, their effectiveness ranges from 10% to 70% every year.
- The "sub-optimal" vaccine is one cause of vaccine hesitancy, according to Adalja. "People extrapolate that to other vaccines, when this is truly specific to the problems we have with the flu vaccine. So, I do think that one of the most important tasks in infectious disease is to develop a universal flu vaccine because it would really move the threat from our biggest pandemic pathogen."
- NIAID announced in 2017 that the vaccine was a priority.
What's happening: Multiple possible universal flu vaccines are in development, with several in trials now.
- There's been success in mapping the flu virus to find better, more conserved parts of the virus that don't mutate as quickly and can be targeted by the vaccines, particularly using new technologies, Adalja says.
- Mascola says the VRC is currently focused on attacking those targets through vaccines that use nanoparticles to allow the size, shape, and other properties to be more precisely controlled. These vaccines tend to be more safe and effective.
- "We're really focused on vaccine constructs, vaccine antigens, vaccine platforms that could really improve what we have now toward the goal of making a vaccine that would be more universal — [with] broader, better, longer duration," Mascola says.
- The VRC is working on different types of vaccines, targeting the whole hemagglutinin protein on the virus or just the stalk of that protein that doesn't change as much, he said. "If we could teach the immune system to generate antibodies to the stalk, that response could be a broader response, a more universal response, than the current licensed vaccines."
- A universal flu vaccine will be the key to herd immunity to influenza, says Sarah Cobey, associate professor at the University of Chicago.
The latest: While trials of universal flu vaccines are ongoing and they don't have published results, Mascola says early human data is showing the vaccine focused on the stem is safe, well-tolerated and generated a "robust immune response" so far.
- If the trial continues to progress there may be a universal flu vaccine available in five years, he said.
- Adalja says while the current vaccines under development aren't "truly universal" because they don't cover 100% of the strains, he adds that they cover a broader range than current vaccines and "look promising."
The big picture: While the current pandemic has focused attention on the novel coronavirus, it also has re-upped interest in pandemic preparedness, particularly against a possible novel influenza strain, Cobey says.
- And, some of the COVID-19 research on vaccine platforms, such as those for mRNA vaccines, could be used to create a better flu vaccine, she adds.
The bottom line: "If there was enough of a divergent strain of influenza that our existing immunity didn't recognize, you could have a severe influenza pandemic. That's the concern ... and this should be even more highlighted by the current COVID pandemic," Mascola says.