The Australian flu – why can’t we control it?

 

The Australian flu epidemic attacked the southern hemisphere in the winter of 2017 and has now, as feared, come to the UK and is rapidly causing a state of chaos for doctors, hospitals and the NHS in general.

Britain is facing one of the worst flu crises in 20 years. It is estimated that one in five people being hospitalised with flu is suffering from the Australian flu strain, 85 people have already died and according to specialists, this is only the beginning.

 

What is the Australian flu- aka the H3N2 influenza A strain?

Despite prevailing belief, there is no one flu virus. There are actually four closely related viruses, that we have umbrellaed under the term “flu”; influenza A, B, C and D.

When we worry about “the flu” we tend to be talking about influenza A and influenza B. Influenza D is especially found in pigs and cows but cannot infect humans.

Influenza A is the most common type of flu and can be a danger to young children and the elderly. It has been known to be transferred between animals and humans, for example, bird flu and swine flu were both influenza A viruses.

Individual influenza A and B strains are often called after the proteins they carry on their surface – hemagglutinin (H) and neuraminidase (N). These Hs and Ns are continuously changing, hence why year-on-year each winter we come across new types of flu strains circulating. This also explains why we get re-infected every year.

The term Aussie flu or Australian flu refers to one kind of influenza A virus strain, the H3N2 strain. It was dubbed the Australian flu following its damaging effects in Australia during winter 2017. It is now the latest deadly flu strain circulating around the UK.

Every year there are various flu strains that appear, however, H3N2 is having more deadly effects than others and has so far been the cause of death for 85 people in Britain since the beginning of winter 2017.

The H3N2 strain is particularly violent due to its severe symptoms, its prolonged recovery time and its tolerance to the normal flu vaccine. The CDC estimates that the flu vaccine is only 20-30% effective against the H3N2 strain.

 

Why is the flu vaccine only 20-30% effective against the H3N2 strain?

Although the current flu vaccine we have in the UK is good at protecting us from other strains of flu, we have not yet managed to create an effective one against H3N2. The main reason for this is that producing flu vaccines is a long and complex process.

Every year, the World Health Organisation advise what to put in that year’s flu vaccine. Each flu vaccine tends to be designed to protect against three or four strains that are particularly prominent that year. However, flu viruses mutate quickly and during the time it takes to create a vaccine, the chosen flu strains will have already evolved and developed, and often so much so that the antibodies stimulated by the vaccine are not able to protect against the virus.

Another reason for the failure of flu jabs is the way that they are currently produced. For now, the most common way of incubating the flu virus for vaccine development is in chicken eggs. However, according to GlaxoSmithKline, the H3N2 strain has been particularly difficult to incubate in eggs.

A chicken egg is a different environment to a human body, and consequently, the flu virus in the chicken egg adapts to its surroundings and mutates. Over the course of the development of the vaccine, it can become a different virus to the original flu virus. This, in many cases, makes the vaccine redundant.

These issues have made it very hard for scientists to find effective ways to control mutating flu strains like the H3N2. Various companies across the globe are looking at new and unconventional ways of creating flu vaccines altogether. Some are attempting to develop a more general flu vaccine to protect against all flu strains, as opposed to a selection.

 

Improving the efficiency of the flu vaccine

Seqirus, the vaccine unit of Australian manufacturer CSL, have been looking at growing the influenza virus in cells as opposed to growing the virus in chicken eggs. It is thought that this could be more effective, as growing the virus in cells is more comparable to how the virus would act naturally when it is in circulation.

Additionally, Protein Sciences, a company acquired by Sanofi last year has been manufacturing vaccines in insect cells. The next step for them is attempting to use this technique on a larger scale.

Other scientists worldwide are working on producing a vaccine against all types of flu strains. This would avoid the issue of trying to target individual flu strains and failing because the strains are constantly mutating. One vaccine to combat all flu strains would mean not having to create a new vaccine every year and would protect more people more efficiently against any flu strain.

One example of a company working on this is Vaccitech, a spin-out company from the University of Oxford’s Jenner Institute. They are creating an unconventional type of vaccine that, rather than going after an antibody response, targets the bottom part of the protein on flu viruses to induce a T-cell response.

 

However, although the flu vaccine is a field that has seen an enormous amount of research and development over time, these clinical tests are still in progress. Vaccitech are projecting that their flu vaccine should be ready by 2023. Meanwhile, doctors and specialists are still encouraging people to get the existing flu jab despite its negatives, as it is currently our only solution and some protection is better than none.

 

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