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Variations in viruses

Jack Warren explains why flu viruses are so difficult to defend against, and current methods for fighting them


Imagine a disease that can infect millions of people a year. One that can spread by merely coughing and sneezing. One that an outbreak in 1918 caused the death of at least 50 million people. No, I’m not talking about Ebola, Zika virus or any other disease that tends to dominate the news. I’m talking about the flu.

The flu is caused by the influenza virus, which produces symptoms similar to a common cold, like a runny nose or sore throat, but can be much more serious. Think back to the panic caused by swine flu and bird flu in the last few decades, and you’ll realise the threat is nothing to be sniffed at.

‘Virus’ Source: pixabay

So it’s good news that we have vaccines that can protect us from the virus. Experts across the world work all year round predicting which strains of the flu will be most prevalent in the following winter, and then producing a vaccine that trains our immune systems to fight the three most likely types to turn up. In the last few decades, we have become very good at this.

But the virus isn’t as easily defeated as that. Influenza has an annoying trait of being able to change it’s appearance very quickly. Hence we have to produce totally new flu jabs every year. The viruses carry large, globular proteins on their surfaces that draw the attention of the immune system. But an immune system trained to recognise lollipop-shaped molecules will be no help in tackling a strain with cricket bat-shaped molecules.

Most viruses morph like this, but the flu is very speedy at doing this. By the time it has spread from China to the USA, it will look totally different.

influenza has an annoying trait of being able to change it’s appearance very quickly

Flu’s tricky nature means the World Health Organisation hold off on announcing which vaccine needs to be produced until the February prior to the flu season hits the Northern Hemisphere. This balances the amount of time needed to produce enough of the vaccines with leaving it late enough to be more sure on what we will be fighting.

So how can we better protect ourselves against something that transforms itself so frequently?

‘Injection’ Source: pixabay

One particularly interesting approach is to develop a ‘universal flu jab’. By trying to target the lollipop stick of the target molecule, rather than the lollipop itself, as this doesn’t mutate quite as much. This means many flu strains will have the same target, therefore making a single vaccine work against many different subtypes of the virus. While in theory this is pretty exciting, it’s not (perhaps unsurprisingly) as straightforward as we might hope, but this hasn’t stopped several teams making some huge steps forwards in the last few years.

Another route being investigated is how we can better predict epidemics that might pop up. Computers are often used to determine what will dominate the flu season, and these are getting more and more accurate. The Epidemic Prediction Initiative uses a combination of 28 different models, which is now more accurate than using any single prediction.

target the lollipop stick of the target molecule, rather than the lollipop itself

Collaborating with teams from other disciplines is proving a very good idea. Recent advances in artificial intelligence and machine learning mean that we should soon be able to spot more patterns and then work out how to target them better too.

One team managed to almost exactly predict the flu outbreaks in the USA by taking how much the virus is evolving into account as well. While these aren’t advanced enough yet to predict next year’s outbreak with any great accuracy, they are certainly steps in the right direction.


Zika was a particularly deadly virus that has been hitting headlines for the past year! Read about it here.

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