Research could lead to 'universal' flu vaccine

“Scientists create new flu vaccine that works against many different strains of the virus,” The Independent reports.

This headline, and several others like it, is based on early stage research into the development of alternative flu vaccine technologies. While the results of this research are promising, they do not mean that a universal flu jab has been developed.

The study used a new technique where two proteins are bound together to form a nanoparticle. These nanoparticles stimulated an immune response to a greater variety of flu strains than the currently available flu jab.

It is important to stress that this work was carried out in ferrets not humans. Ferrets do have biological similarities to humans, at least in the way they respond to flu and the flu vaccine, so this is a genuinely intriguing development.

But it will take several years of further clinical trials to assess whether this technique can lead to a safe and effective ‘universal flu’ vaccine for humans.

Currently, the best bet is to take measures to protect yourself during peak flu season. This includes regularly washing your hands, staying home from work or school if you have the flu and getting a yearly flu jab if you’re at risk of serious complications.

Where did the story come from?

The study was carried out by researchers from the Vaccine Research Center, part of the US National Institutes of Health (NIH) and was supported by the NIH. The lead researcher is now based at Sanofi, a pharmaceutical company that manufactures vaccines.

The study was published in the peer-reviewed journal Nature.

BBC News reports the findings of the study in an appropriate manner. The headline “Universal flu jab 'edges closer'” and the warning that “a vaccine which could defeat all flu was a long way off” properly convey the stage this research is at.

But most other reporting on this study failed to do this. For example, The Independent’s headline “Scientists create new flu vaccine that works against many different strains of the virus” is premature and does not reflect the early stage of technology development that this research is at.

While the work is a step towards a universal vaccine, the technology has not yet been developed and tested to a point at which it could replace the annual flu jab.

What kind of research was this?

This was a laboratory and animal study that investigated a new approach to generating flu vaccines.

Current vaccines are designed to protect against three strains of the flu virus that health experts expect to be widely circulating in the population during any given year.

This current approach is limited by the fact that the annual vaccine may not match the most common strains circulating that year. This approach also means seasonal flu vaccinations must be carried out annually to ‘catch-up’ with any changes in flu strains.

The aim of this study was to develop a technique targeting a protein that is common to a wide variety of flu viruses, thus priming the body to mount an immune response to a broader range of flu strains.

This research is at a fairly early stage, but it does suggest that it may be possible to develop a universal flu vaccine. The technology will need to be tested further in animals. It will then need to be proven to be safe and effective for people during clinical trials before a ‘universal jab’ could be made available.

What did the research involve?

Researchers fused together two proteins – one, called ferritin, which stores iron and occurs naturally in our blood; the other, called haemagglutinin (HA), which is a viral protein responsible for the initial stages of flu infection. It works by attaching the flu virus to the cell it is going to infect.

Individual ferritin proteins naturally come together and form a smooth hollow ball. Researchers thought that fusing ferritin and haemagglutinin would result in a similar sphere with HA spikes, and that the resulting nanoparticle would be recognised by antibodies.

They further thought that when the spheres were injected into animals they would trigger the body to mount an immune response against a range of flu strains.

To test the ability of this ferritin-haemagglutinin nanoparticle to initiate an immune response, researchers first immunised ferrets with either a traditional flu vaccine or the new complex. They measured the HA titres (titres indicate the number of antibodies the body has produced that recognise the HA spike) three weeks later, and compared the titre levels between the two groups.

Researchers then tested the ability of the ferritin-haemagglutinin complex to protect against a range of flu strains. Three groups of ferrets (one immunised with the new complex, one immunised with a traditional flu vaccine and one non-immunised control group) were exposed to a variety of flu strains. The immune response across the groups was then compared.

What were the basic results?

The researchers found that when the ferritin and haemagglutinin proteins were fused together, the proteins self-assembled into a nanoparticle with haemagglutinin spikes sticking out from the core.

When the nanoparticle was exposed to an antibody known to target HA, the researchers found that it bound to the antibody in a similar manner as traditional flu vaccines.

They say this indicates that the newly developed ferritin-haemagglutinin particles resembled the HA spike of the flu virus, which, in theory, could stimulate an immune response against a flu infection.

Three weeks after immunisation, the researchers found that ferrets injected with the ferritin-haemagglutinin nanoparticle had levels of antibodies (antibody titres) that were approximately ten times higher than those seen in the ferrets injected with the traditional flu vaccine.

They also found that a single injection of these nanoparticles produced an immune response similar to two immunisations with a traditional vaccine.

When challenged with different flu strains, the ferritin-haemagglutinin immunised group of ferrets demonstrated an earlier immune response than the control group, and suffered less weight loss than both the traditionally immunised and non-immunised ferrets, which researchers say further demonstrates the protective effect of the new ferritin-haemagglutinin particles.

How did the researchers interpret the results?

The researchers conclude that this new HA-nanoparticle technology “represents a foundation for a new generation of influenza vaccines and could be adapted to create vaccines for a wide variety of pathogens”.

Conclusion

This is promising research that takes us a step closer to developing a universal flu vaccine. Despite headlines suggesting otherwise, no universal jab has yet been developed.

The researchers say that this new particle is capable of enhancing the body’s immune response compared with the currently used flu vaccine, and that the new complex offers protection against a wider variety of flu strains.

It is important to remember that this research is still in its early stages. This technology development may well lead to the generation of a new type of vaccine. However, significant research is still required to move from the current stage to an available universal flu jab.

Until then, the advice for protecting yourself during flu season remains the same:

• Practise good hygiene – wash your hands regularly, clean commonly used surfaces and use tissues when you cough or sneeze.
• Consider getting an annual flu jab if you are at risk of severe flu complications. Groups at high risk for complications include those over the age of 65, pregnant women and people who have a weak immune system or underlying health condition such as a chronic heart or respiratory disease. 

Read more about preventing the spread of flu.