The world’s first widespread human testing of a universal flu vaccine against influenza has begun in the UK. Rather than focusing on antibody production, the new vaccine stimulates the immune system to boost influenza-specific T-cells and aims to protect the elderly who are particularly susceptible.

Influenza virus causes acute respiratory infections and is the most likely cause of large epidemics in humans among all known pathogens. Influenza viruses mutate rapidly and can cross from animals to humans, generating novel, potentially pandemic strains. Furthermore, flu is easily transmitted through aerosol and even people showing mild or no symptoms can infect others. The worst flu outbreak in many years in Australia and New Zealand proves that existing vaccines are not enough to prevent epidemics.

The new vaccine was developed by Oxford University’s Jenner Institute with Vaccitech, a spin-out company from the institute. People aged 65 and over will be asked to take part in a study supported by the National Institute for Health Research and delivered by the University of Oxford in Berkshire and Oxfordshire. Researchers believe the vaccine could have a major impact on the worldwide fight against the virus.

Annually, epidemics are estimated to result in about 3 to 5 million cases of severe illness, and about 250.000 to 500.000 deaths. Last winter’s vaccine cut the risk of flu by about 40% in adults under the age of 65 but it was barely effective for people over 65, since the immune system weakens with age. Even if people do end up sick, researchers believe the new vaccine could nevertheless help reduce the severity and duration of the illness.

“Every year, flu in older adults causes serious illness and sometimes death. We want to improve the situation, but in order to do that we need volunteers to help us test a new vaccine. If you are invited to take part, please consider doing so,” Professor Sarah Gilbert, Professor of Vaccinology at the University and co-founder of Vaccitech, said for Oxford News.

Under the microscope, the flu virus looks like a “spherical cushion” with lots of pins sticking out of it. The existing flu vaccines contain modified surface proteins – the heads of the pins – to stimulate the body’s immune system to produce antibodies. But as the virus changes so do the surface proteins, most commonly haemagglutinin and neuraminidase, which renders existing influenza vaccines ineffective against new viruses. Scientists struggle with taking the “best guess” at what each new strain of flu will be like.

The new vaccine uses the core proteins of the virus, inside the capside. These core proteins are highly preserved among most influenza A viruses, providing researchers with the opportunity to create a universal vaccine that could even work across different species of animals (eg. bird and swine flu). Humans get infected by both influenza A and B, but it is the A subtype that causes the majority of severe illnesses and deaths. The experimental vaccine stimulates the body to induce T cells, against these core proteins. Previous research has found that these T-cells can help fight more than one type of flu virus.

Prof Sarah Gilbert believes that using her team´s vaccine alongside the current one could help. Half of the 500 volunteers enrolled in the clinical study will receive the usual seasonal flu vaccine and a placebo, while the other half will get the new experimental one instead of the placebo. The trial will take two years to complete and if further studies go well the vaccine could be licensed for wider use in the future.

“We expect that the protection from the new vaccine will last longer than a year, but we will need to test that with more clinical trials in the future. It is possible that, in future, vaccinations against flu might be given at longer intervals – maybe every five years instead of every year. But first, we have to test protection in the first flu season following vaccination,” Gilbert told the BBC.

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By Andreja Gregoric, MSc