Scientists have discovered what they believe might be a blue print for a universal flu vaccine, and it is based on a natural immunity some people already have.
Like all viruses, influenza is tricky. A central characteristic of a virus is that it can change its makeup. As a result, our attempts at creating vaccines to boost our immunity and fight viruses like flu are unfortunately always trying to catch up. As soon as we develop a vaccine for one strain, we will learn that the virus has mutated and is unperturbed by our defenses.
What if scientists could find a way to create a shot that would be capable of improving our immunity in all cases, no matter the strain of the flu virus our body is fighting? Well, scientists think they might just have found a way.
Swine Flu Tests Yield Key T Cell Finding
A write-up of a study published in the journal Nature Medicine tells how the 2009 pandemic involving the strain of swine-origin H1N1 flu, referred to as swine flu, offered UK scientists a rare chance at determining what characteristic, if anything, those who had a naturally higher level of immunity to the flu shared.
To determine this, 342 healthy adults — staff and students at Imperial College London, in fact — were recruited and monitored for the length of the outbreak.
At the start of the study, the volunteers were asked to donate blood samples and were asked to provide nasal swabs. They were then sent emails every three weeks asking them to fill in a survey about their current health. If they were experiencing flu symptoms, they were asked to provide another nasal swab.
What scientists found when they analyzed the data they received during this trial was that those participants who on starting the trial had more of a particular kind of virus killing immune cell, CD8 T cells, were the ones who suffered milder or no symptoms when they became infected during the course of the experiment.
To understand why this is exciting, we have to first know a little bit about how traditional flu shots work.
What Vaccines Do and What T Cells Do Differently
Our current crop of flu vaccines provoke the immune system into recognizing and fighting the virus but they do so by, in essence, recognizing the outside structures or face of the virus. Change the face and the body cannot recognize this stranger. As a result it isn’t prepared to act as effectively. That’s when flu can spread at an alarming rate.
However, CD8 T cells do something quite different.
Professor Ajit Lalvani of the National Heart and Lung Institute at Imperial College London, who led the study, explains:
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. The 2009 pandemic provided a unique natural experiment to test whether T cells could recognize, and protect us against, new strains that we haven’t encountered before and to which we lack antibodies. 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.
What is particularly encouraging in this case is that scientists already know how to stimulate T cell production and so a vaccine could be available within as little as five years.
Currently, the World Health Organization is concerned that the H7N9 and H5N1 avian influenza viruses may reemerge this flu season, in particular because recent tests suggest the emerging H7N9 strain in China is particularly virulent and as such may pose a risk to global health. At least 135 people have been infected with avian flu and 44 people have died since the outbreak began in Spring of this year.
With a T cell based vaccine, however, even such emergent strains that have never been seen before would be guarded against, at least to a certain extent.
Encouraging Test Results But What About This Winter’s Flu Season?
Of course, this is all theoretical at the moment, and further studies and tests will have to be carried out before any such vaccine could make its way onto the market. Also, scientists don’t yet know for certain how much of an immunity such a vaccine would provide and so questions remain about whether a universal vaccine like this could provide immunity equivalent to those vaccines tailored to each virus. However, the possibility of a universal vaccine is tantalizing.
In the meantime, Dr Richard Pebody, who conducts flu surveillance duties at the the Respiratory Diseases Department at Public Health England, is quoted as giving both an optimistic nod to these findings, and sage advice on practical steps for the public to take in the meantime, saying:
Influenza is continually evolving and it is difficult to predict what strains will emerge each year. These findings contribute to the science to determine if it is possible to develop a universal vaccine to protect a population against all strains of flu. The study results are a timely reminder for people to get their flu jab this winter.
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