An experimental vaccine that has been developed based on messenger RNA (mRNA) technology, the same technology used in Pfizer’s and Moderna’s COVID-19 vaccines, would protect against all flu viruses. This “multivalent” vaccine contains antigens from all 20 known subtypes of influenza A and B viruses, so it could become a universal vaccine to prevent infection and prevent future influenza pandemics, according to its creators, scientists from the Perelman School of Medicine, University of Pennsylvania.
“The idea here is to have a vaccine that gives people a basic level of immune memory for various strains of flu, so that there is much less illness and death when the next flu pandemic hits,” said Scott Hensley, professor of Microbiology at the Perelman School of Medicine and lead author of the study, which has been published in Science.
Tests in animal models showed that the vaccine significantly reduced flu symptoms and protected them from death, even when the animals were exposed to different flu strains than those used to make the vaccine. Hensley and her lab collaborated on the study with the lab of mRNA vaccine pioneer Dr. Drew Weissman, Roberts Family Professor of Vaccine Research and director of vaccine research at Penn Medicine.
A universal vaccine to prevent flu pandemics
Pandemics caused by influenza viruses still cause large numbers of deaths, even if the tens of millions who died worldwide from the 1918-19 ‘Spanish flu’ are missing. Birds, pigs, and other animals can carry flu viruses, and an outbreak that becomes a pandemic can be triggered at any time when one of these strains jumps to humans and develops mutations that make it easier for it to spread from person to person. .
“We believe that this vaccine could significantly reduce the chances of contracting a serious influenza infection”
Available flu vaccines are “seasonal”—meaning they protect against recently circulating strains but not new strains that could cause a pandemic later—and making effective vaccines to prevent a future pandemic is complicated because they It is not known which subtype of influenza virus will cause it.
The Penn Medicine researchers’ strategy has been to vaccinate with immunogens—a type of antigen that enhances immune responses—of all known influenza subtypes for broad protection. Although they do not expect the vaccine to provide “sterilizing” immunity that completely prevents viral infections, the study results show that it generates a memory immune response that can rapidly recover and adapt to new pandemic viral strains, dramatically decreasing severe illness and death from infections.
The mRNA vaccine generated high levels of antibody levels in the mice, which were maintained for at least four months, and they reacted strongly to all 20 influenza subtypes. This antibody response in the mice was strong and widespread, regardless of whether they had been exposed to the flu virus before or not.
“Our studies indicate that mRNA vaccines can provide protection against antigenically variable viruses by simultaneously inducing antibodies against multiple antigens.” “It would be comparable to the first-generation SARS-CoV-2 mRNA vaccines, which were directed at the original Wuhan coronavirus strain,” Hensley said. “Unlike later variants like omicron, these original vaccines did not completely block viral infections, but continue to provide long-lasting protection against severe disease and death.”
Hensley and his colleagues are currently preparing human clinical trials and, if successful, they envision the vaccine could be useful in achieving long-term immunological memory against all influenza subtypes in people of any age, including children. little ones. “We believe that this vaccine could significantly reduce the chances of getting a serious flu infection,” Hensley said.
mRNA technology, useful against influenza viruses
Adolfo García-Sastre, Director of the Institute for Global Health and Emerging Pathogens of the Mount Sinai Hospital in New York, in statements to the Science Media Center Spain (SMC) affirms that: “It is a very interesting study. It demonstrates the ability to develop multivalent mRNA vaccines that are capable of immunizing against 20 or perhaps more different antigens at the same time. In this case, they are influenza virus antigens that encompass all possible subtypes and variants of the influenza virus, including those with pandemic potential.”
“Current flu vaccines do not protect against flu viruses with pandemic potential. This vaccine, if it works well in people, would do this.” “The studies are preclinical, in experimental models. 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”.
Estanislao Nistal, according to statements made to the same medium, is of the opinion that: “It is enormously complex to formulate a vaccine against flu viruses that can protect us, not only against the current circulating viruses in humans, but also against possible viruses that can produce a future pandemic. That vaccine is the so-called universal flu vaccine.
“The researchers present a strategy similar to that used to generate the mRNA vaccine against SARS-CoV-2, but in which they introduce messenger RNA from the 20 versions of the hemagglutinins of type A and B influenza viruses that could give rise to a virus with the possibility of infecting us. 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 far from appreciably similar to those of the influenza virus. sequences included in the vaccine.
“All of this implies that it is possible to potentially have a universal vaccine that is easy and quick to build that could be very useful in the event of a pandemic outbreak due to a new influenza virus. Although they do not mention it in the article, this vaccine could also be very useful in preventing influenza in animals that may suffer from it, and reduce the risk of zoonoses among animals in a context of global health”.
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