Universal flu vaccine may provide pandemic breakthrough

The scientific community has hailed a breakthrough which may see a universal flu vaccine which will offer protection against all 20 known subtypes of influenza virus.

Researchers from the Perelman School of Medicine at the University of Pennsylvania, said the vaccine provided broad protection from otherwise lethal flu strains in initial tests, and thus might serve one day as a general preventative measure against future flu pandemics,

The “multivalent” vaccine uses the same messenger ribonucleic acid (mRNA) technology employed in the Pfizer and Moderna SARS-CoV-2 vaccines. This mRNA technology that enabled those COVID-19 vaccines was pioneered at Penn. Tests in animal models showed that the vaccine dramatically reduced signs of illness and protected from death, even when the animals were exposed to flu strains different from those used in making the vaccine.

“The idea here is to have a vaccine that will give people a baseline level of immune memory to diverse flu strains, so that there will be far less disease and death when the next flu pandemic occurs,” said study senior author, Scott Hensley, a professor in of Microbiology at in the Perelman School of Medicine.

The breakthrough has been welcomed by scientists across the world.

Dr Andrew Freedman, reader in Infectious Diseases and Honorary Consultant Physician, Cardiff University, said: “The investigators have used the same mRNA technology that was so successful in the rapid development of several of the COVID-19 vaccines, to produce a vaccine that has the potential to protect against all 20 of the different ‘flu virus lineages.  This would not be possible using the conventional protein vaccines in current use  One of the main problems with those vaccines is the need to adapt them each year to the particular viruses expected to be circulating.

“This vaccine has only been tested in animals to date & it will be important to investigate its safety and efficacy in humans.  However, it does seem a very promising approach to the goal of producing a universal ‘flu vaccine as well as vaccines that protect against multiple members of other viral families such as rhino- and corona- viruses”

Adolfo García-Sastre, director of the Institute for Global Health and Emerging Pathogens at Mount Sinai Hospital in New York, said: “This is a very interesting study. It demonstrates the ability to be able to develop multivalent mRNA vaccines that are able to immunise against 20 or perhaps more different antigens at the same time. In this case, these are influenza virus antigens that encompass all possible influenza virus subtypes and variants, including those with pandemic potential.

“Current influenza vaccines do not protect against influenza viruses with pandemic potential. This vaccine, if it works well in people, would achieve this.

“The studies are preclinical, in experimental models. They are very promising and, although they suggest a protective capacity against all subtypes of influenza viruses, we cannot be sure until clinical trials in volunteers are done.”

Raúl Ortiz de Lejarazu y Leonardo, Professor of Microbiology, scientific advisor and director emeritus of the National Influenza Centre in Valladolid, added the study offered a huge potential in the battle to prepare for future pandemics.

“The search for a universal influenza vaccine began in 2012-13, although there had been different approaches before that,” he explained. “Among the latest is trying to discover and obtain antigens (epitopes) that are present in the majority of variants of an influenza subtype (conserved epitopes). In this way a universal response can be achieved and even if the variable epitopes change, the response to the conserved epitopes will remain.

“The new study is well conceived and comprehensively conducted.”

However, he said there was a need to be cautious.

“The main limitation is that it is done in mice and ferrets, very good animal models for flu, but animal models. So with sarcasm (always healthy in science), mice and ferrets around the world should congratulate themselves because they now have a universal flu vaccine for themselves.

“In all seriousness, there is a long, sometimes insurmountable, way to go from the animal model to humans. The type of response, the extent of the response, the persistence, etc. are not similar.

“The first [phase 1] human trial of a universal influenza vaccine was published two years ago, but people were enraptured by the new coronavirus.”