Estanislao Nistal
Professor of Microbiology at the Faculty of Pharmacy
The study is highly relevant and well conducted, providing very interesting data on the possibility of generating a universal vaccine against the different influenza viruses.
Influenza disease in humans is mainly caused by influenza A and B viruses. Currently, the influenza A virus in humans can be further subclassified into H1N1 and H3N2 subtypes, depending on the class of the haemagglutinin (there are 18 different versions in total) and neuraminidase (there are 11 different versions) proteins that the viral particles have on their surface. Also influenza B viruses can have two different versions of haemagglutinin on their viral particles. There are numerous subtypes of influenza A viruses infecting animal species other than humans that contain the different versions of haemagglutinin and neuraminidase mentioned above.
It is enormously complex to formulate a vaccine against influenza viruses that can protect us, not only against currently circulating viruses in humans, but also against potential viruses that could produce a future pandemic. Such a vaccine is the so-called universal influenza vaccine.
The researchers present a strategy similar to that used to generate the messenger RNA vaccine against SARS-CoV-2, but in which they introduce messenger RNA from the 20 versions of the haemagglutinins of type A and B influenza viruses that could give rise to a virus with the potential to infect us. The results show that this vaccine is able to induce 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 significantly different from the sequences included in the vaccine.
All of this implies the potential for an easily and rapidly constructed universal vaccine that could be of great use in the event of a pandemic outbreak of a novel influenza virus. Although not discussed in the article, this vaccine could also be of great use in preventing influenza in animals that may suffer from it, and reducing the risk of zoonosis among animals in a global health context.
The article does not yet present data on the possible advancement of this vaccine to a next phase in humans, where not only efficacy, but also adverse effects, dosage or short- and long-term immunity should be demonstrated.
Another limitation is that they need to further study the role of T-lymphocytes in disease protection. Activation of CD4 T cells is important for an optimal humoral antibody response.