Why we’ll never beat the flu virus (unlike Zika)

Zika, which has been linked to a huge increase in the number of babies born with small heads in Brazil, may be the scariest virus around just now, but it’s actually going to be much easier to tackle and eradicate than flu, which has managed to evade our best attempts to wipe it out for decades.

Every year in February, scientists from around the world gather at the Head Quarters of the World Health Organisation in Geneva and decide which three flu types are likely to cause the most problems in the next flu season. This is based on what has happened during the previous winter (our summer) in the Southern Hemisphere, which gives an early indication of which flu viruses are likely to affect us next. The vaccines are then developed and given to people who need them in October or November, before the ‘flu season starts in the Northern Hemisphere.

But don’t expect the experts to get it right most of the time or even some of the time. As happened in 2015, we very often get our predictions wrong simply because the virus mutates faster than we can keep up. Zika, on the other hand, which is linked to brain damage in newborns in 23 countries including Brazil, is a virus that has hardly changed in 50 years. Even now, it remains perfectly possible that Zika has not mutated at all, but has just flourished in its new home (it used to be confined to Africa). It has simply exploited densely populated urban areas where many people collect rain water to drink and store it near their homes. This makes it easy for the Zika-carrying Aedes aegypti mosquitos, which bite anytime during the day, to breed right next to people and pass infected blood quickly from person to person.

This means it should be relatively easy to create a vaccine that works for a long time and prevents Zika infection taking hold. GlaxoSmithKline plc have announced that they are fast tracking feasibility studies to see if they can use existing vaccine technology to work on a Zika vaccine.

Canadian scientist Gary Kobinger, a scientist who worked on the Ebola vaccine and part of a consortium working on a Zika vaccine, has revealed that the first stage of human testing could start in early August – meaning it could be ready by autumn 2016. He said that the vaccine he is working on mimics the virus, triggering the body’s immune system.

Flu jabs have to change constantly, sometimes even during a season. When this happens, vaccines don’t protect against a mutated form of virus because they are designed to fight another slightly different version. In early 2015, scientists pinpointed Influenza A type H3N2 and two others which were thought to be less of a problem. Although H3N2 is not as virulent as some other strains of flu, it mutates very easily, which is what seems to have happened. Around 20 per cent of patients were infected with mutated strains is higher than we expect, normally just two per cent.

Even without mutations to worry about, the scientists are doomed to be one step behind the flu contagion. The flu cycle is a constant merry go round with new fly bugs constantly developing around the equator where the flu virus can thrive all year round. Every now and them, a super version like H1N1 or bird flu, proves very resistant and causes a world wide pandemic – the last one we had was in 2009.

Flu pandemics have occurred every few decades, in 1918, 1957, 1968 and 2009, but there is good reason to believe that they may actually happen more regularly in future. This is due to the population explosion, bringing people in much closer proximity to one another allowing the virus to spread, and the increasing number of people who expect to eat meat protein, often living in close quarters with pigs, fowl and other animals that are known to harbour flu which can cross the species barrier.

The good news is that we do produce vaccines that work most of the time for most of the people, and innovations like Tamiflu can protect people further who at high risk of infection. Treatment is now better too so people are more likely to survive outbreaks.

Flu pandemics will return again and again, but the Zika pandemic should be over when a vaccine is created, sadly leaving an appalling legacy to remember it by.

Professor John Oxford
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