Scientists test messenger RNA technology for universal flu vaccine

An experimental vaccine provided broad protection against all 20 known subtypes of influenza A and B viruses, which cause the common cold, in initial tests in mice and ferrets.

The results pave the way for a universal vaccine against the disease that could help prevent future pandemics, according to a US study published on Thursday (24).

The two-dose vaccine employs the same technology as messenger RNA (mRNA) used in the Covid-19 vaccines developed by Pfizer and Moderna. The immunizer provides small lipid particles containing mRNA instructions for cells to create replicas of the so-called hemagglutinin proteins that appear on the surfaces of the influenza virus.

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“The idea here is to have a vaccine that gives people a baseline level of immune memory for different strains of flu, so there will be much less illness and death when the next flu pandemic hits,” said study leader Scott Hensley. from the Perelman School of Medicine at the University of Pennsylvania, in a statement.

Unlike standard flu vaccines that provide one or two versions of hemagglutinin, the experimental vaccine includes 20 different types in hopes of getting the immune system to recognize any flu viruses 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 remained unchanged for at least four months, according to a report published in the journal Science.

The vaccine reduced signs of illness and protected from death even when the ferrets were exposed to a different type of flu that is not in the vaccine, the researchers said.

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Moderna and Pfizer have mRNA flu vaccines in late-stage human testing, and GSK and partner CureVac are testing an mRNA flu vaccine in an early-stage human safety assessment. These vaccines are designed to protect against only four newly circulating influenza strains, but theoretically they could be changed each 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 efficacy and possible regulatory requirements for a vaccine against possible future viruses that are not currently circulating, wrote Alyson Kelvin and Darryl Falzarano of the University of Saskatchewan in Canada in a commentary published with the study.

While the promising results with the new vaccine “suggest a protective capacity against all influenza virus subtypes, we cannot be sure until clinical trials in volunteers are completed,” said Adolfo García-Sastrem, director of the Institute of Global Health and Pathogens. Emergents from Mount Sinai Hospital in New York, in a statement.

(Edited by Christine Soares and Bill Berkrot)