2012: The Next Flu Pandemic?

While many public health scares are associated with a degree of speculation, the devastating impacts of a flu pandemic are very well characterised. Over the last century influenza has been responsible for millions of deaths globally, and more recently we have been faced with newer, highly lethal strains that present a real threat to our existing vaccination strategies. Despite our solid understanding of the virus and radical advances in medicine, the possible impact of a future pandemic is impossible to predict.

Influenza infection occurs by aerosol transmission, either by direct contact or highly contagious respiratory droplets that can remain suspended in the air and travel up to a metre in length. It is a frequent visitor to Northern Hemisphere countries during winter months, especially effecting the old and very young. Annual deaths from seasonal epidemic flu range from 0.25-0.5 million, and every year the NHS spends around £100 million on flu vaccinations alone, a staggering value that doesn’t even take into account the societal costs due to absences from employment: To the health economist, healthcare professional and patient, seasonal flu is far from a trivial issue.

What is more alarming than seasonal ‘drift’ is the rarer antigenic ‘shift’, which has occurred four times in the last century. A pandemic arises when a strain of human and animal influenza co-infect a host, typically a pig, allowing segments from the two genomes to shuffle. Like shuffling a deck of cards, this produces a new combination of viral RNA to which humans have had no previous exposure. Unlike seasonal flu, such pandemics cannot be predicted in advance, rendering timely vaccine production unviable.

Although the death toll from pandemics is on the decline, we must still remain vigilant. Viruses are able to evolve rapidly, accruing mutations that provide them with a competitive edge over the human immune response. 1990 to 2010 saw only 27 cases of swine flu, known to virologist as ‘H3N2v’. However, there have since been 309 cases confirmed by the US Centre for Disease Control (CDC). In addition several strains of influenza are now resistant to some of the best antiviral drugs we have available. If these strains acquired the ability to transmit from person-to-person more efficiently, it is certainly possible that we could see another worldwide pandemic with the number of casualties extending into the millions.

Such speculation has prompted research into the production of a universal flu vaccine that could offer protection against any strain of the virus. Professor John Oxford, director of Retroscreen Virology, has been conducting large-scale trials for Flu-v, which he describes as “a universal vaccine that could reduce the need for people to have vaccines each year”. Of course pushing this drug through to market will take several years, with the possibility of it failing along the way. Furthermore, influenza is just one example of many viral threats, and other emerging viruses, such as Ebola, could prove to be an even bigger problem.