Influenza, or more commonly referred to as the flu, is a highly contagious virus that affects the respiratory system. Because it is so contagious, it can affect thousands of people annually. In fact, somewhere between 5% and 20% of the United States population will contract the virus each year (2). However, despite its frequency of occurrence, the flu is not always a deadly disease. Of the people who are infected, there is an average of 200,000 hospital visits a year, and, depending on the strain, the number of flu-related deaths can range from 3,000 to 49,000 (2). The following fact is what makes the flu so dangerous though: the virus mutates every year. Every year doctors scramble to create a vaccine that will protect the public from the different flu strains that hit during flu season; they do not always make the appropriate vaccine, though, and that is when fatalities can accumulate. This leads to a pandemic.
The most recent influenza pandemic was the H1N1 virus that occurred in 2009. Also known as swine flu, this virus hospitalized thousands; everyone was caught off guard. On top of that, scientists found that symptoms varied drastically among similar individuals with the swine flu. Some people experienced no symptoms while some were hospitalized. This has shown with the other strains of influenza as well, and this was a question that scientists desperately were trying to find an answer to: What decides whether one is going to be asymptomatic? After the onset of the swine flu in 2009, a group of researchers at Imperial College London began a study hoping to answer this question, and the results that they found were groundbreaking.