Scientists funded by the National Institutes of Health have developed a universal flu vaccine that uses groundbreaking messenger-RNA technology to build immunity against 20 known types of influenza, the agency said Tuesday.
If successful in trials, the vaccine would be a major upgrade from the yearly flu shot that tries to block a handful of strains.
“These vaccines are formulated each year to protect against up to four circulating strains of influenza virus, and they generally do a good job of this,” the NIH said in a blog post. “What they can’t do is prevent future outbreaks of more novel flu viruses that occasionally spill over from other species into humans, thereby avoiding a future influenza pandemic.”
A seasonal shot that can induce immunity against all known subtypes of flu would help the world avoid catastrophic seasons.
The experimental vaccine hasn’t been tested in people, but the concept “has shown great promise in advanced preclinical studies,” according to the NIH.
“Human clinical trials will hopefully start in the coming year,” the agency said. “The researchers don’t expect that this universal flu vaccine will prevent influenza infection altogether. But, like COVID-19 vaccines, the new flu vaccine should help to reduce severe influenza illnesses and deaths when a person does get sick.”
Prior attempts to land a universal flu vaccine relied on antigens — proteins that produce an immune response — that had been conserved and tend to stay the same over time.
Yet traditional vaccine manufacturing processes, such as growing flu viruses in eggs and isolating proteins, made it difficult to target more than four subtypes of flu, according to the NIH.
A research team led by Scott Hensley of the Perelman School of Medicine at the University of Pennsylvania decided to leverage mRNA, a technology used in the leading vaccines for COVID-19 from Pfizer-BioNTech and Moderna.
The technology uses the shots to deliver snippets of genetic instructions inside a lipid shell — a small bubble of fat, essentially — and teach the body to recognize and fight pathogens.
Using mRNA, the Perelman team was able to target proteins on the viral surface known as hemagglutinin (H) for 18 types of influenza A and two types of influenza B.
“What makes mRNA so nifty for vaccines is that all you need to know is the letters, or sequence, that encodes the genetic material of a virus, including the sequences that get translated into proteins,” the NIH said. “More study is needed, of course, but early indications are encouraging. The vaccine generated strong and broad antibody responses in animals. Importantly, it worked both in animals with no previous immunity to the flu and in those previously infected with flu viruses.”
NIH said the research team hopes to launch a phase 1 trial in humans in 2023.
“This mRNA vaccine candidate got a lot of press, but there are other mRNA universal influenza vaccines that are further along the development pipeline,” said Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security. “It is true, though, that the success of the mRNA vaccine platform for [the coronavirus] vaccines gave this technology a very high profile and generated a lot of interest in using this technology for other infectious diseases.”
Scientists have worked on mRNA technology for decades, but it wasn’t deployed in a widespread fashion until the COVID-19 pandemic.
Teams at Pfizer and Moderna were able to design a vaccine targeting the novel coronavirus shortly after it appeared in China. They raced to hold human trials during 2020 and got them authorized for emergency use.
Some people remain leery of the shots, which may limit uptake if the universal flu vaccine is authorized. Skeptics fear mRNA is too new, while others are disappointed the COVID-19 shots seem to prevent only severe disease instead of blocking infection outright.
