Universal Flu Vaccine: A Step Forward

Great news! We have made another step in the direction of creating a universal flu vaccine. This has always been a goal but an elusive one. For many years now we have had to make an educated guess each year as to what the most prevalent strain of flu will be in the upcoming season, production of a vaccine for that one strain is then ramped up through the summer to try to ensure a good supply for the winter. Remember, each single dose of flu vaccine is created inside a chicken egg. Think how many millions of eggs must be needed each year just to help us stop getting flu!

Anyway, sometimes our best guess isn't as good as it could have been, plus there is no protection from the many other strains of flu that may or may not be doing the rounds at any given time; so it's an imperfect system. Then why haven't we made a universal vaccine before? Well, let's picture an influenza virus. Imagine a ball with lots of lollypops sticking out of it. The sweet, delicious head of the lollipop is the part that can change and vary and evolve and is what makes them so darned hard for our immune systems to recognise and adapt to. If you've heard terms like H5N1 and H3N2 then these refer to this part. The stick part of the lollipop (the haemagglutinin stem) is unchanging and seems to be the same in every strain of flu so far studied. It would seem sensible to create a vaccine that targets this unchanging stalk component rather than the ever evolving blobby head, but this has never been possible because the stalk is physically difficult to access. Imagine flying over a dense forest canopy and trying to find a way to hack at a tree trunk.

In the past some clever people have found a way to decapitate the stalk and so free it up for attack, but it turned out that the stalk then sort of just fell apart leaving nothing for our immune systems to attack. In a new paper in Science a team from Leiden, Germany, detailed how they were able to decapitate the stalk but then modify it so that it was stable thereby leaving a target. Then they created an antibody that is able to recognise the stem and provoke an immune response and protection from the virus.

Mice infected with the lethal H5N1 strain of influenza were fully protected. Macaques still had a bout of the flu but the symptoms were much less severe than normal. The concept, then, has been proved. The next stage will be human trials, but these typically take several years to perform so we are still someway from a universal vaccine for ourselves. It's a prize worth waiting for, though; half a million people generally die from flu each year, and that's in a good year. Last year a mutation in the H3N2 strain, which the vaccine was targeted against, resulted in a vaccine that provided little protection and a commensurate spike in deaths. Perhaps in a decade the flu vaccine will be a part of the childhood vaccination program and that will be all we need for the rest of our lives, that would be a truly wonderful achievement.

Three dimensional influenza structure; image used with permission