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Is a long-acting flu vaccine expected?

 
, medical expert
Last reviewed: 02.07.2025
 
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15 May 2024, 06:49

Developing a long-lasting flu vaccine could be extremely beneficial to public health, and research is moving closer to achieving this goal.

A study published in the journal Science Translational Medicine found that creating a vaccine that further targets a region of the hemagglutinin (HA) glycoprotein that is less prone to mutation could be a path to creating long-term flu vaccination options.

The researchers tested their vaccine in mice and ferrets and found that it provided better protection than traditional vaccination. Although more research is needed, this successful test points the way forward for the development of a long-term flu vaccine.

Problems in developing effective influenza vaccines

Influenza is a common infection that affects billions of people each year. The World Health Organization also estimates that influenza causes 3 to 5 million cases of severe illness and 290,000 to 650,000 respiratory deaths each year. Some people are more at risk for severe illness or complications from influenza, including children under age five and older adults.

Flu viruses cause influenza, and these viruses change. The current strategy for protecting against influenza is to use annual flu vaccines. Experts create these vaccines based on which flu viruses they think will be most common during the flu season.

Changes in influenza viruses, particularly in surface proteins such as hemagglutinin (HA), represent one of the challenges in creating a long-lasting vaccine.

Dr. Yoshua Quinonez, a board-certified internist at Manhattan Medical Offices, noted the following:

"Challenges with flu vaccines include the need to update them every year because the virus changes, certain parts of the virus that make the vaccine less effective, and the inability to protect against all types of flu viruses. It's also difficult to ensure that everyone can get the vaccine. But getting a flu shot can help reduce the number of people who get sick, protect those who can't get vaccinated, and perhaps one day there will be a vaccine that is effective against all types of flu. Boosting your immune system's response to the flu shot may also help protect against more types of flu viruses."

Is it possible to create a long-term universal flu vaccine?

The researchers in the current study note that annual flu vaccines help create antibodies that target specific regions of the HA head. However, this region is often subject to frequent mutations.

So if they could find a way to target a region of HA that varies less, like the stalk, they might be able to create a vaccine that could protect against many strains of flu. However, while this has been attempted before, it has not been effective in generating a strong response in the head region.

So the researchers wanted to create a vaccine that could produce antibodies targeting the head and stem to provide long-term immunity against multiple flu strains. They ultimately created a vaccine based on an HA antigen mixture. This vaccine contained a mixture of HA proteins with a conserved stem and various mutations in the key head region.

The researchers in this study tested the vaccine's effectiveness in mice and ferrets. They compared the response to traditional vaccine approaches.

They found that their vaccine elicited a better antibody response than a control vaccine. The vaccine even provided protection when mice were exposed to lethal doses of the virus. It also offered protection against several strains of the H1 virus.

However, this newly developed vaccine appeared to be most effective after receiving an initial dose and a booster dose, rather than a single dose.

Dr. Linda Yancey, an infectious disease specialist at Memorial Hermann Health System in Houston, commented on the study's findings:

"This is a significant step towards a universal flu vaccine. Developing such a vaccine has been a goal of researchers for many years. It has proven challenging, so it is encouraging to see solid progress being made. Scientists are still working on developing the building blocks of the vaccine. We will probably not see changes in clinical practice based on this for several years. But every step in the right direction brings us closer to a universal vaccine."

Limitations of the study and further research

This study has limitations, mainly because animal testing is different from human testing. The animals also had no previous flu vaccinations or exposure to flu, which could have affected the results observed. The researchers note that most people have some level of prior immunity to flu, which could minimize or affect the response to this type of vaccine. The study also looked at only one H1 HA, so it’s unclear how the approach would affect other HAs. Additionally, not all animal experiments were blinded.

The researchers also acknowledge that further research is needed to better understand the underlying mechanisms and confirm the reasons for the observed response. They acknowledge that “protection from infection may not always correlate with a reduction in classical antigen responses.”

Even if this potential vaccine is developed, experts, government agencies, and medical professionals will need to address issues of distribution and acceptance. Dr. David Cutler, a board-certified family physician at St. John's Medical Center in Santa Monica, California, noted:

"While safety and effectiveness are the primary concerns, vaccine acceptance is also an important issue. Currently, only about 50% of adults receive the flu vaccine. Any improvement in effectiveness may be offset by reluctance to receive a new vaccine. It is the job of our public health agencies to convince people that the benefits of approved vaccines far outweigh their risks. So, while scientists may develop new, improved vaccines, the benefits to society may not be realized unless the vaccines are administered."

However, the study does raise the potential for developing a long-lasting flu vaccine. This could make it easier to maximize the vaccine's impact and ultimately minimize the harmful health effects of flu.

Quinonez expressed hope for the results and noted the following:

"A new flu vaccine could work better than older ones. If it works in people as well as it does in animals, it could mean fewer people get the flu each year. It could also lead to a vaccine that works against all types of flu, which would be a huge step forward in keeping people healthy."

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