The 2009 swine flu epidemic a monstrous mutation of pig, bird and human flu viruses was estimated to have killed more than 280 000 people. (Supplied)
'The Holy Grail is to create a universal vaccine that would be effective against all strains of flu," says Professor Ajit Lalvani, from Imperial College London's National Heart and Lung Institute.
Lalvani and his team followed nearly 350 people during the 2009 swine flu epidemic, taking blood and nasal swabs, looking for virus markers. From this, they have found a possible basis for a vaccine.
It is a big ask – not only are there many different strains of the influenza virus, but they mutate and new strains emerge every year. These annual epidemics cause about three- to five-million cases of severe illness and about 250 000 to 500 000 deaths worldwide, according to the World Health Organisation (WHO).
We are not talking about the sniffles caused by the common cold, which is also a virus, but is more irritating than life threatening.
Vaccines, which are recommended by the WHO, contain parts of specific strains that will be prevalent in a given flu season, which enables the body to recognise the virus and fight it. But the mutating virus is always a few steps ahead of the vaccine.
The 2009 swine flu epidemic – a monstrous mutation of pig, bird and human flu viruses – was estimated to have killed more than 280 000 people. However, for researchers from the Imperial College London, the epidemic offered a natural laboratory to investigate flu.
The research, published on September 22 in scientific journal Nature Medicine, "followed 342 healthy adults through the United Kingdom pandemic wave", the study authors wrote. They measured the subjects' CD8 T-cell count. A CD8 T-cell is a type of white blood cell that fights viruses.
Lalvani, who headed up the study, says: "The immune system produces these CD8 T-cells in response to usual seasonal flu. Unlike antibodies, they target the core of the virus, which doesn't change, even in new pandemic strains."
Because the 2009 swine flu epidemic had not been encountered before – either by our bodies or by researchers – it "provided a unique natural experiment to test whether T-cells could recognise and protect us against new strains [of influenza]".
At the beginning of the epidemic, Lalvani's team recruited staff and students at Imperial College London to take part in this experiment.
For two flu seasons, they donated blood and nasal swabs, responded to three weekly surveys about their health, and sent researchers nasal swabs if they felt sick.
The researchers found that people who had a higher CD8 T-cell count at the beginning of the epidemic avoided severe illness.
"Our findings suggest that by making the body produce more of this specific type of CD8 T-cell, you can protect people against symptomatic illness. This provides the blueprint for developing a universal flu vaccine," Lalvani says.
"We already know how to stimulate the immune system to make CD8 T-cells by vaccination. Now that we know these T-cells may protect, we can design a vaccine to prevent people getting symptoms and transmitting infection to others. This could curb seasonal flu annually and protect people against future pandemics."
Professor Sarah Gilbert, a vaccine specialist with Oxford University's Jenner Institute, told the Mail & Guardian on Tuesday that the study does not mention vaccine development. "The new paper confirms findings from earlier studies. There is nothing specific on vaccine development. It is a study of natural immune response."
While "it is not that different from what other people have done … it does give information about what to look at when making a vaccine".