The Universal Flu Vaccine, Closer

The universal flu vaccine is closer. The prestigious magazine “Science” published yesterday the preliminary results of a new vaccine prototype that aims to be used against all types of flu. It is based on the technology of messenger RNA (mRNA) with lipid nanoparticles, the same used by vaccines of Pfizer Y modern against COVID-19, and includes antigens from all 20 known influenza subtypes. It would help prevent not only seasonal flu, but also avian flu in humans, which has a mortality rate close to 30%, and flu viruses with pandemic potential that may emerge in the future.

According to World Health Organization, each year up to 650,000 people die from respiratory illnesses related to seasonal flu. A scientific team led by Claudia Arevalofrom the Institute of Immunology of the University of Pennsylvania (United States), has presented in “Science” the results of preclinical trials in mice and ferrets of its “icosavalent” mRNA vaccine.

As he explains in statements to SMC Victor Jimenez CidProfessor of the Department of Microbiology and Parasitology of the Faculty of Pharmacy of the Complutense University of Madrid, this is the first high-impact publication that presents a successful strategy for a “universal” vaccine based on mRNA against influenza.

The scientists focused on a little-changing region of the virus called the “stalk” of the spike. “If we manage to neutralize the invariable region of the stem, we would have a universal vaccine, a weapon against the variation capacity of the virus,” argues Jiménez Cid.

As it explains Stanislaus Nistal, virologist and professor of Microbiology at CEU San Pablo University, influenza in humans is mainly caused by type A and type B influenza viruses. Currently, the type A influenza virus in humans can in turn be subclassified into the H1N1 and H3N2 subtypes, depending on the class of hemagglutinin (there are 18 different versions in total) and neuraminidase (11 different versions) proteins that the viral particles have on their surface. Also the type B influenza virus can present two different versions of hemagglutinin in its viral particles. There are numerous subtypes of influenza A viruses that infect animal species other than humans that contain the different versions of hemagglutinin and neuraminidase mentioned above.

“The results show that this vaccine is capable of inducing a robust antibody-mediated response in mice and ferrets (animal models widely used to study influenza) against different subtypes of influenza viruses, including viruses that are not significantly similar to the sequences included in the vaccine,” says Nistal to SMC. “All this implies that you can potentially have a universal vaccine of easy and quick construction that could be very useful in the event of a pandemic outbreak due to a new influenza virus (…) The article does not yet present data on the possible advance of this vaccine to a next phase in humans, where not only efficacy should be demonstrated, but also adverse effects, dose, or short- and long-term immunity.”

For his part, Raúl Ortiz de Lejarazu, scientific adviser and emeritus director of the National Influenza Center of Valladolid, told SMC that the most important novelty “lies in the fact that it uses many antigens from different hemagglutinin subtypes (all of which exist, including those of bats)”, but remember that this study “is done in mice and ferrets, very good animal models for influenza, but animal models”, and stresses that “there is a very long way to go, sometimes insurmountable, from the animal model to the humans”.

agree on this point Adolfo Garcia-Sastre, director of the Institute for Global Health and Emerging Pathogens at Mount Sinai Hospital in New York. “The studies are preclinical, in experimental models –points to SMC–. They are very promising and, although they suggest the ability to protect against all subtypes of influenza viruses, we cannot be sure of this until clinical trials are carried out in volunteers”.

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