A 13-year-old Canadian girl got so sick with H5N1, or bird flu, at the end of 2024 that she had to be put on a ventilator. Around the same time, a Louisiana adult was diagnosed with the first “strong” case in the US
As bird flu continues to increase, many are wondering what tools—namely vaccines—we should use to combat it if we need to intervene in such a way.
Dr. William Schaffner, professor of infectious diseases at Vanderbilt University Medical Center and spokesman for the Infectious Diseases Society of America, says: “Public health and infectious disease people around the world are watching. bird flu very carefully. “The concern is that this virus would be able to attach to human cells and spread throughout. That would be opening the door to a new epidemic for sure.”
For this to happen, the H5N1 virus would have to develop the right mutations that allow it to easily infect human cells – a process that could easily happen if someone were to become infected with H5N1 influenza, for example , allowing the two viruses to exchange genetic information and recombine into a virus that can easily infect and spread among humans.
Fortunately, that has not happened yet, but health workers are not waiting. Vaccination work continues to protect the public in the event of an outbreak, and earlier this year, Dr. Mandy Cohen, director of the US Centers for Disease Control and Prevention (CDC), pointed to mRNA as the preferred platform for the shot since vaccines can be made and distributed quickly.
Here’s the latest on efforts to develop a new bird flu vaccine.
Is there an H5N1 vaccine yet??
Several vaccines target H5N1, and the national stockpile contains doses of all of them. The shots target the H5N1 strain that was circulating when the vaccines were made years ago, but health experts expect they will still protect against severe disease.
“Fortunately, current vaccinated patients reduce circulating in vitro strains,” wrote health officials from the US National Institute of Allergy and Infectious Diseases in a Dec. 31 article. New England Journal of Medicine. A small number of healthy volunteers were vaccinated with these H5N1 vaccines, and the antibodies they produced appeared to neutralize the circulating virus in laboratory tests. But these vaccines have not yet been tested in a clinical trial, as there have not been enough H5N1 infections in humans to compare vaccinated and unvaccinated individuals.
What about the mRNA vaccine for H5N1?
There hasn’t been one, but several companies – including Moderna, Pfizer and GlaxoSmithKline (in partnership with CureVac) – are working on such a shot. In July, the US government’s Biomedical Advanced Research and Development Authority (BARDA) awarded Moderna $176 million to develop its improved mRNA H5N1 vaccine. All mRNA vaccine candidates are in early stages of testing in humans for safety and efficacy.
The vaccines rely on the same mRNA technology that was used to create the COVID-19 vaccine. In recent weeks, scientists led by a team at the CDC reported that an H5N1 mRNA-based vaccine helped ferrets to mount strong antibody responses against the virus and survive a lethal dose in ferrets. when they did not receive the vaccine.
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Dr. Drew Weissman, director of vaccine research at Penn Medicine and winner of the 2023 Nobel Prize for his pioneering work in mRNA technology for vaccines, and his colleagues also reported results that encouraging about the vaccine they made and tested in ferrets. The vaccine, which targeted the H5N1 strain that causes recent infections in chickens and cattle, prevented severe illness and death from H5N1 in ferrets. Animals that were not vaccinated did not survive.
“The real advantage of mRNA vaccines in an epidemic setting is the ability to renew the vaccines when needed,” says Scott Hensley, a professor of microbiology at the University of Pennsylvania Perelman School of Medicine who worked with Weissman to develop the vaccine. injection. “The beauty of mRNA is the transient ability to transform the vaccine.”
How soon could an updated vaccine be available?
While developing an mRNA vaccine would only take months, conducting clinical trials could take much longer. “We know the vaccines are well tolerated and safe because they were in the context of COVID-19,” says Hensley. But any new antigen needs to be tested.
In order to avoid delays in providing vaccines to the public in the event of an epidemic, governments should invest in large, back-to-back trials before an epidemic occurs, says Hensley. He says: “It would be investing in something that you are not sure will cause an epidemic. But it is a decision that governments have to make. In my opinion, it would be money well spent in dealing with the virus- be aware of the possibility of this virus.”
One way to avoid that delay and reduce the number of people who get sick from avian influenza is to develop and distribute a more targeted vaccine. Influenza comes in four main types—A, B, C, and D—and two, A and B, cause most illnesses in humans. (H5N1 is type A.) Hensley developed a vaccine agent capable of detecting all 20 types of influenza A and B—including H5N1—and found that it produced strong immune responses. immunity in mice and ferrets. In addition, when the vaccinated ferrets were exposed to different strains of influenza within those subtypes, they still developed positive immune responses against them.
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Although the vaccine did not protect the animals from infection, they did not get seriously ill. “What it does is boost the immune system to respond and clear the virus faster,” says Hensley. “So the idea would be to immunize the community with this type of vaccine that would reduce the initial severe death in the event of an epidemic. That would buy time for specially adapted vaccines that could be developed and used as boosters. Schools wouldn’t have to be closed, and people would still get infected but not die.”
The National Institutes of Health is supporting trials of this vaccine, which could change the way we vaccinate against the flu and other emerging threats. Hensley says that if proven safe and effective, such a shot would be given to babies so their immune systems can be trained to recognize more flu strains early. That would allow them to develop faster and more effective immune responses to vaccines and infections as they age.
Who should be vaccinated against H5N1?
Because the CDC says the risk of bird flu remains low for the general public, there are no recommendations for anyone in the US to be vaccinated against H5N1 at this time. Some experts believe that dairy workers and others who have close contact with potentially infected animals, such as chickens and cattle, should be vaccinated to protect them from infection, but health workers the beauty of the US has not yet made this decision, noting that the full understanding of the dangers of H5N1 to people and the benefits of the vaccine is not yet fully clear.
Finland has offered people at high risk of exposure to bird flu – including those in the fur industry who handle wild boars and those in the poultry industry – a vaccine made by Seqirus, which uses an old vaccine technology that includes a strain unemployed. of the virus.
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