HUMANS & INFLUENZA: ARE WE MAKING OURSELVES MORE VULNERABLE TO A GLOBAL PANDEMIC? Charlotte Furness (OHS) In January of this year, the World Health Organisation (WHO) released its list of the ‘Ten Threats to Global Health in 2019’. On this list was ‘Global influenza pandemic’, however what made this threat different was that the others on the list are known ongoing problems, yet influenza was the only one with uncertainty, as even WHO admits they can’t be sure of “when it will hit and how severe it will be.” On this list were a range of threats, from Dengue to air pollution and climate change . Subsequent monitoring systems are in place to detect any potential pandemic-causing strain of influenza, however could it be possible that human causes are speeding up the process of heading towards a global outbreak? Influenza is a virus, with several different strains. Most commonly known is seasonal influenza, which tends to occur in the coldest seasons in both the Northern and Southern Hemispheres. It is prevalent year-round along the equator . There are 3 strains of seasonal influenza: A, B, and C, yet influenza A and B pose a much greater threat of a large outbreak. Humans can also be infected by influenza that affects animals, known as ‘zoonotic influenza’ and while these currently don’t have the capacity to cause large scale outbreaks, if a mutation of the virus allowed it to spread effectively between humans, then the repercussions would be serious . An influenza pandemic is when a new variation of the virus previously not seen among humans emerges. If many people aren’t immune to this new variation then the virus will transmit rapidly, potentially causing a rapid, large-scale outbreak of influenza . An influenza pandemic could be deadly because the pandemic causing virus will be one that can easily infect people and that few people have immunity towards, causing the virus to spread rapidly. Flu pandemics on a global scale have been seen multiple times, but most notably in 1918. It’s estimated that around one third of the global population was infected with the virus, and up to 50 million people died as a result, which is more than double the death toll of the First World War, which was around 17 million. Each year, over half a million people are killed by seasonal influenza and 1 billion are affected by the virus . Recently, an increasing number of influenza positive viruses have been found over the past 20 years, as seen in Figure 1, meaning the likelihood of an outbreak is increasing as there are more variations of the virus which can mutate.
Figure 1 A growing population means that more people are vulnerable to influenza, as well as more people which the virus can infect, making it harder to contain outbreaks. The most vulnerable are the very old, the very young, and pregnant women . As Figure 2 and Figure 3 show, the population of the US has increased and the age structure has changed, with a large increase in the number of dependents, who are the most susceptible to influenza. A larger number of vulnerable people means more people to treat and more people to vaccinate. In lower income countries, the rate of population growth tends to be higher, leaving them more susceptible to outbreaks as their healthcare systems often lack resources needed to treat outbreaks of the virus.
Figure 2
Figure 3 A recent study has linked climate change and warmer winters to worse flu seasons. It indicates that milder winters are followed by heavier and earlier influenza seasons, as fewer people are infected with the virus during the warm winter, so more people are susceptible to it entering the next season . As climate change increases global temperatures, warmer winters will become more common, meaning the effects of future
