The Spread of the Swine Flu in 2009
According to this article by the CDC, the swine flu started in the United States by two isolated cases in California, with the origins of the disease in Mexico. However, since both cases started in elementary school-aged children, which most likely allowed the infected children to come in contact with many other students before the cases were identified. This exemplifies the model we discussed in class, such that patient (or, in this case, patients) zero, come into contact with k healthy people with a p rate of infection. The epidemic spread because of the large initial k value before cases could be identified, allowing kids who may have been exposed to the disease to return home, possibly spreading it to their families and schoolmates.
This first wave of people spread the flu to their coworkers, and so on and so forth. This allowed swine flu to become an epidemic and sweep across the US. Eventually, the swine flu virus was declared a pandemic by the World Health Organization. Eventually, a variation of the influenza vaccine was developed that was effective against the disease, which was able to stop the spread of the virus.