Is a flu vaccine with long-term effectiveness on the horizon?

ISLAMABAD, May 15 (Online): Influenza viruses cause billions of flu infections and thousands of deaths across the globe each year.
Developing an effective, long-term flu vaccine is challenging because of viral mutations. Researchers are interested in what strategies they can use to get around this problem.

Results from a recent study suggest that targeting multiple areas of the virus’ proteins may be the key to creating a flu vaccine that offers long-term immunity, specifically focusing on an area that experiences less mutation.
Developing a long lasting flu vaccine could be highly beneficial for the health of society, and research is getting closer to this goal.

A study published in Science Translational Medicinefound that developing a vaccine that additionally targets an area of the hemagglutinin (HA) glycoprotein that experiences less mutation may be how we reach long-term flu vaccination options.

Researchers tested their vaccine in mice and ferrets and found it offered better protection than conventional vaccination. While more research is required, this successful test directs how to proceed with creating a long-term flu vaccine.

Challenges of developing effective flu vaccines
The flu is a common infection, affecting billions of peopleTrusted Source each year. The World Health Organization also estimates that the flu is responsible for 3-5 million cases of severe illness and 290,000 to 650,000 respiratory deaths yearly. Certain people are more at risk for severe illness or complications from the flu, including children under five and older adults.

Influenza viruses cause the flu, and these viruses change. Currently, the strategy for protection from the flu is the use of annual flu vaccines. Experts create these vaccinesTrusted Source based on what influenza viruses they believe will be most common during flu season.

Changes in influenza virusesTrusted Source in influenza viruses are part of the challenge of creating a long-term vaccine. These changes often occur in the virus’s surface proteins, like hemagglutinin (HA).

“The difficulties with flu vaccines include needing to update them every year because the flu virus changes, certain parts of the virus making the vaccine less effective, and not being able to protect against all types of the flu virus. It’s also hard to make sure everyone can get the vaccine. But getting the flu shot can help reduce how many people get sick, help protect those who can’t get the shot, and maybe one day there will be a vaccine that works for all types of the flu. Making the immune system respond better to the flu shot could also help protect against more types of the flu.”

Is it possible to create a long lasting, universal flu vaccine?
The researchers of the current study note that annual flu vaccines help create antibodies that target specific areas of HA globular head. However, this region often experiences frequent mutation.

Thus, if they could figure out a way to target an area of the HA that doesn’t change as much, the stalk, they may be able to create a vaccine that could protect against many flu strains. However, while this has been tried in the past, it has not been effective in also eliciting an effective response in the head region.

Thus, researchers wanted to create a vaccine that could produce head and stalk-directed antibodies to offer long-term immunity against multiple flu strains. Ultimately, they made an HA antigenic mixture–based vaccine. This vaccine contained a mixture of HA proteins with a conserved stalk region and various mutations at a key site in the head.

Researchers in this study tested the vaccine’s effectiveness on mice and ferrets. They compared the response to conventional vaccine approaches.

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

However, this newly developed vaccine appears most effective after receiving an initial prime dose and a booster rather than just a single dose.

“This is a nice step in the direction of a universal flu vaccine. Producing one has been the goal of researchers for years. It has proven to be a complex and difficult task, so it is nice to see solid progress being made towards it. At this time scientists are still working on developing the building blocks of a vaccine. We probably won’t see any changes in clinical practice based on this for a few years. But every step in the right direction brings that universal vaccine a little closer.”

Study limitations and continued research
This study has limitations, mainly because animal testing differs from testing something in people. These animals had also not experienced any previous flu vaccine or flu exposure, which could have affected the observed results. Researchers note that most people have some pre-existing immunity to influenza, which could minimize or influence the response to this type of vaccine. The study also only looked at one H1 HA, so it’s unclear how the approach would impact other HAs. In addition, not all animal experiments were conducted in a blinded manner.

Researchers also acknowledge that further study is required to understand more of the underlying mechanisms and confirm why they observed the response they did. They acknowledge that “the protection from infection may not always be correlated with decreasing classical antigenic site-directed responses.”

Even if this potential vaccine is developed, experts, government agencies, and health professionals will need to address distribution and acceptance. Non-study author David Cutler, MD, board certified family medicine physician at Providence Saint John’s Health Center in Santa Monica, CA, noted the following:

“While safety and effectiveness are the major concerns, vaccine uptake is also an important issue to consider. Presently, only about 50%Trusted Source of adults receive a flu vaccine. Any improvement in effectiveness could be offset be reluctance to receive a new vaccine. It is the role of our public health agencies to convince people that the benefits of approved vaccines greatly exceed their risks. So, while scientists may develop new, improved vaccines the benefit to society may not be realized if the vaccines do not get administered.”

However, the research sets up the potential development of a long-term flu vaccine. This could make it easier to maximize the vaccine’s impact and ultimately minimize the detrimental health effects of the flu.

Quinones was hopeful about the results and noted the following:

“The new flu vaccine might work better than the old ones. If it works in people like it did in animals, it could mean fewer people getting sick from the flu each year. It might also lead to a vaccine that works for all types of the flu, which would be a big deal for keeping people healthy.”