A step closer to a universal flu vaccine?

Imagine a single dose of vaccine that prepares the body to fight every known strain of influenza. This is the so-called universal flu vaccine that scientists have been trying to create for decades.

A new study describes the success of animal testing of just such a vaccine, offering hope that it could protect the nation from future influenza pandemics. Like the Covid vaccine, the influenza vaccine relies on mRNA.

Although at an early stage, having only been tested in mice and ferrets, this vaccine provides important evidence that a single injection can be used against an entire family of viruses. The approach could potentially be used against other virus families, possibly including coronaviruses.

Vaccines don’t replace the annual flu shot, but they do provide protection against severe illness and death from the potential pandemic threat.

Scott Hensley, an immunologist at the University of Pennsylvania who led the study, said:

“If there’s a new flu pandemic tomorrow, with a vaccine like this that was widely adopted before that pandemic, we might not have to shut everything down.” explained about vaccines It was published in Science last week.

By the age of 5, most children have had the flu multiple times and develop some immunity, but only against the strains they encounter.

“Exposure to influenza as a child creates long-lived immunological memories that can be recalled later in life,” Dr. Hensley said. However, “we live the rest of our lives depending on the random chances we were infected with as a child.”

Current influenza vaccines protect against seasonal influenza but offer little protection against new strains that may emerge as a pandemic threat. vaccines provided little protection against the virus. However, older individuals exposed to the H1N1 strain in childhood developed only mild symptoms.

Scientists have long attempted to create vaccines that would infect children with all types of influenza they might encounter in the future. I have received

Broadly speaking, there are 20 subgroups of influenza, each representing thousands of viruses. Current vaccines can target up to four subgroups. However, the vaccine contains all 20 and can be produced more quickly.

Researchers found that the vaccine induced high levels of antibodies against all 20 influenza subtypes in ferrets and mice.

If the vaccine works similarly in humans, “it will provide broader coverage of influenza viruses, not just those that are circulating, but the potential escapes from animal reservoirs that could trigger the next pandemic.” It’s something,” said Alyson Kelvin. A vaccinologist at the University of Saskatchewan in Canada said:

There are drawbacks to packing 20 targets into one vaccine. Antibody levels in test animals were lower than those given individual strain-targeted vaccines. However, the levels effective against influenza were still sufficiently high.

Because new pandemic strains of influenza may differ from the 20 targets included in vaccines, researchers also tested against imperfectly matched viruses. Vaccines still offer strong protection, suggesting that they can prevent at least severe illness from the new pandemic influenza virus, if not infection.

This phenomenon is similar to the current Covid vaccine. His latest Omicron variant is very different from its ancestor virus, and while the original vaccine does not prevent infection, it still helps protect most people from severe illness.

This quality could be a particular advantage of mRNA vaccines, Dr. Kelvin said. Conventional influenza vaccines only target specific viruses for which they are designed. However, mRNA vaccines appear to generate antibodies that protect the body against a wider range of viruses than the viruses they contain.

Experts have pointed out some key caveats and questions that must be answered before a vaccine becomes a viable candidate.

Animals in the study developed protection equally against all 20 strains of influenza. But “these animals have never had the flu before,” says Richard J. Webby, a flu-hi virus expert at St. Jude Children’s Research Hospital in Memphis.

Dr. Webby said this complete lack of immunity to influenza only applies to very young children. Older people are exposed to different strains throughout their lives, and it is not clear whether immune responses to universal vaccines are highly uniform.

“The evidence for pudding is what happens when it enters humans and how entering the pre-immune population distorts the response to it,” Dr. Webby said.

Designing a universal vaccine for different age groups is difficult if needed. Some experts say it is also important to see how long such vaccine protection lasts.

Ted Ross, director of global vaccine development at the Cleveland Clinic, said: “If we have to keep updating it, it may not add to the benefits of current vaccine practices.”

The next step for the vaccine is testing it in monkeys and humans. However, proving its effectiveness can be difficult. “How do we evaluate and regulate a vaccine whose target is not circulating?” Dr. Kelvin said.

Perhaps the vaccine could be tested in small sporadic outbreaks or in poultry workers who are at risk of contracting the bird flu virus, she said.