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Scientists test universal flu vaccine

A bandage, a vial of vaccine and a cotton ball.

June 25, 2021—Clinical trials of a new kind of flu vaccine are underway, and scientists say this type of experimental vaccine could one day make yearly flu shots a thing of the past.

A new approach to fighting the flu

Flu viruses are always changing. And in any given year, different strains may circulate more or less widely than others. So designing a flu shot that protects people against the most dangerous strains is like trying to hit a moving target.

The flu shots we get right now must be updated each year. And scientists have to choose just 3 or 4 strains to include each time. In years when the vaccines are not well-matched to the viruses that are going around, the shots may be less effective.

That's why researchers have been working on developing a universal flu vaccine instead. Universal vaccines are designed to give long-lasting protection from many flu virus strains—not just a few. Such a vaccine might even guard against flu viruses that don't exist yet, including those that might cause a future flu pandemic.

Researchers with the National Institute of Allergy and Infectious Diseases have begun testing a candidate vaccine, called FluMos-v1, in phase 1 human trials.

How does it work?

Flu viruses have specific, unique proteins that appear on their outer surface. One of those is hemagglutinin (HA). Each strain of HA contains a head and stem. The head is what changes from season to season, so that's what seasonal flu vaccines typically target. But the stem goes largely unchanged from year to year. So it's a more tempting target for a universal flu vaccine.

Like the seasonal flu vaccine, FluMos-v1 focuses on four main flu strains. But by presenting 20 different copies of the HA protein, it is designed to elicit a stronger, more stem-focused response from the immune system. The result could be a vaccine that protects people for much longer than just one flu season.

In early studies, FluMos-v1 produced a strong immune response in animals that were given the vaccine. And it worked better than a seasonal flu shot at guarding against flu strains not included in the vaccine.

What's next?

For the phase 1 trial, a small group of about 35 adult volunteers will receive either a seasonal flu vaccine or the candidate vaccine. Scientists will monitor the volunteers for side effects as well as evaluate how they generate antibodies.

If found to be safe, the vaccine could go on to phase 2 trials where it would be tested in hundreds of volunteers.

In the meantime, remember: Getting a seasonal flu shot is the best way to protect yourself from the flu. Test your knowledge by taking our quick flu quiz.

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