Trial of a universal flu vaccine shows promise

While there are insinuations that the flu is a mild disease not to be worried about, it is in fact a disease that kills hundreds of thousands a year and can cause a variety of complications. This is despite the existence of the yearly flu vaccine and the diseases’ allegedly moderate symptoms.

One of the difficulties of preventing the flu lies in how diverse of a disease it is. Making matters worse, minor changes in the virus’ genetic code, caused by random mutations, prevent long-term immunity. When a flu vaccine for the year is created, scientists have to predict which strains will be prominent that year. While they are often reasonably accurate, sometimes they miss. When they do, the flu shot is less protective than it could be, and infection rates climb.

This also means that when a pandemic occurs, a vaccine against that particular strain must be created from scratch. As we’ve all seen with the case of COVID-19, the time spent doing this is very expensive in terms of lives.

A new study published in Nature Medicine suggests that this problem may soon be one of the past, as a candidate for a universal flu shot, one effective against a wide variety of possible strains, has just passed its first clinical trials with flying colors.

The shot you received this year works by giving your body a weakened form of the flu virus and allowing your body to fight it off. A flu virion is a little ball with hemagglutinins (HA), stalks with rounded heads that latch on to cells, sticking out of them. A typical flu shot primes your body to recognize the head of this structure.

However, these heads change their form very frequently. Your body typically can’t tell it’s still the flu after these changes, and you need a new shot each year. This new vaccine candidate focuses on the HA’s stalk, which changes far less often than the head. Since these stalks are similar for very many flu strains, it would also be quite effective against more than just the few which are currently included in a seasonal shot.

Our bodies tend to focus on the head when attacking a flu virus or learning about it from a vaccine. It can be challenging to make it focus on the stalk.

To get around this, the researchers in this study combined commonly seen stalks with bizarre heads taken from types of flu typically seen in birds. This odd flu strain, half-bird flu and half-human flu, would be like nothing the body has seen before. Notably, the immune system would notice the familiar stalk before it figured out the head was part of an invading virus.

As a result of this, the immune system attacked all parts of the virus and started making antibodies for attacking the stalk in the future. Blood was later taken from the test subjects who had the vaccine. The tests showed the vaccine had “induced remarkably high antistalk antibody titers.” Mice injected with these antibodies and then infected with the flu showed better outcomes than those that merely got the flu, suggesting the antibodies continued effectiveness.

This is a very promising outcome. Dr. James Cherry, a vaccine expert and professor at the University of California, explained his appreciation of the study to NBC: “I think this is a great first step. And I think it will be really the future of flu vaccines.”

This study, while a very exciting success, was a small first-stage clinical trial. It will likely be another two years before larger scale, multiyear tests can be carried out to further demonstrate the vaccine’s effectiveness. You’re not going to be able to get this anytime soon. Issues of funding may also slow its development, as various groups are working on their own universal flu vaccines.

Additionally, the study focused on vaccines against viruses with a particular kind of HA stalk. More tests will be required to see if this works against flu strains with different stalks. However, lead author Florian Krammer argues that this is proof that “you can develop a vaccine strategy that produces stalk-reactive antibodies in humans.”

While there is still a way to go, the possibility of a universal flu shot, effective against many flu strains that exist or may exist, is higher than ever.