- Studies could pave the way for a universal flu shot that could help prevent future pandemics.
- Universal vaccination would eliminate the guesswork involved in designing annual vaccines months in advance of each flu season.
- Vaccine-induced antibody levels were stable for at least four months.
In preliminary tests on mice and ferrets, an experimental vaccine provided broad protection against all 20 known influenza A and B virus subtypes, potentially paving the way for a universal flu shot that could help prevent future pandemics, according to a study published in the United States on Thursday.
The two-dose vaccine utilizes the same messenger RNA (mRNA) technology as the Covid-19 injections developed by Pfizer (PFE.N) in collaboration with BioNTech (22UAy.DE) and by Moderna (MRNA.O). It provides minute lipid particles with mRNA instructions for cells to produce replicas of so-called hemagglutinin proteins, which are found on the surfaces of influenza viruses.
Universal vaccination would not put a stop to flu seasons, but it would eliminate the guesswork involved in designing annual vaccines months in advance of each flu season.
In a statement, Scott Hensley of the Perelman School of Medicine at the University of Pennsylvania said, “The idea here is to have a vaccine that will give people a baseline level of immune memory to diverse flu strains so that there will be far less disease and death when the next flu pandemic occurs.”
In contrast to traditional flu vaccines, which give one or two variants of hemagglutinin, the experimental vaccine contains twenty variants in an effort to train the immune system to detect any influenza virus it may face in the future.
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In laboratory trials, the immune systems of vaccinated animals recognized the hemagglutinin proteins and guarded against 18 distinct influenzas A strains and two influenza B strains. Vaccine-induced antibody levels were stable for at least four months, according to a publication in the journal Science.
According to the researchers, even when the ferrets were exposed to a different strain of influenza not included in the vaccination, the immunization prevented disease and death.
Moderna and Pfizer have mRNA influenza vaccines in late-stage human trials, and GSK (GSK.L) and partner CureVac (5CV.DE) is evaluating an mRNA influenza vaccine in an early-stage human safety experiment. These vaccines are designed to protect against only four types of influenza currently circulating, but they could theoretically be updated annually.
If successful in human trials, the universal influenza vaccination would not always prevent infection. Hensley stated that the objective is to provide long-lasting protection against serious sickness and death.
Alyson Kelvin and Darryl Falzarano of the University of Saskatchewan, Canada, said in an editorial accompanying the findings that it is unclear how efficacy and potential regulatory requirements for vaccination against potential future viruses that are not currently circulating can be determined.
In a statement, Adolfo Garcia-Sastre, director of the Institute of Global Health and Emerging Pathogens at Mount Sinai Hospital in New York, said that while the promising results with the new vaccine “suggest a protective capacity against all subtypes of influenza viruses, we cannot be sure until clinical trials in volunteers are done.”