An experimental vaccine provided broad protection against all 20 known subtypes of influenza A and B viruses in initial tests in mice and ferrets, potentially paving the way to a universal flu vaccine that could help prevent future ones pandemics, according to a US study published Thursday.
The two-dose vaccine uses the same messenger RNA (mRNA) technology used in the COVID-19 injections developed by Pfizer PFE.N with BioNTech 22UAy.DE and by Moderna MRNA.O. It delivers small lipid particles that contain mRNA instructions for cells to make replicas of the so-called hemagglutinin proteins that appear on the surfaces of flu viruses.
A universal vaccine would not mean the end of flu seasons, but would replace the guess work that goes into developing annual vaccinations months before flu season each year.
“The idea here is to have a vaccine that gives people a basic level of immune memory to various strains of flu, so there will be far less illness and death when the next flu pandemic occurs,” the leader of the study Scott Hensley of the Perelman School. of Medicine from the University of Pennsylvania in a statement.
Unlike standard flu shots that provide one or two versions of hemagglutinin, the experimental vaccine includes 20 different types in the hope that the immune system will recognize any flu virus it may encounter in the future.
In laboratory experiments, the immune systems of vaccinated animals recognized the hemagglutinin proteins and defended against 18 different strains of influenza A and two strains of influenza B. Vaccine-induced antibody levels were maintained without changes for at least four months, according to a report published in the journal Science.
The researchers said the vaccine reduced signs of illness and protected against death even when the ferrets were exposed to a different type of flu that was not in the vaccine.
Moderna and Pfizer have mRNA flu vaccines in late-stage human trials, and GSK GSK.L and partner CureVac 5CV.DE are testing an mRNA flu vaccine in an early-stage safety trial in humans These vaccines are designed to protect against only four recently circulating strains of flu, but could theoretically be changed every year.
The universal flu vaccine, if successful in human trials, would not necessarily prevent infection. The goal is to provide lasting protection against serious illness and death, Hensley said.
Questions remain about how to judge the efficacy and potential regulatory requirements of a vaccine against potential future viruses that are not currently circulating, Alyson Kelvin and Darryl Falzarano of the University of Saskatchewan, Canada, wrote in a commentary published with the study.
Although the promising results of the new vaccine “suggest a protective capacity against all subtypes of the influenza virus, we cannot be sure until clinical trials are carried out in volunteers”, Adolfo García-Sastrem, director of the Institute of Mount Global Health and Emerging Pathogens. Sinai Hospital in New York, said in a statement.
Reporting by Nancy Lapid; Editing by Christine Soares and Bill Berkrot