The premise of the film revolves around a new virus, a chimeric combination that leaps from bats to pigs to humans, then spreads worldwide, passing from human to human.   The director attempts to follow the epidemiology of viral spread, bringing in the Centers for Disease Control (CDC) and the World Health Organization (WHO) perspective to track the virus and predict total mortality.  Using subplot, the film follows the lives of several individuals from the beginning of transmission to the development of the vaccine.  The lives of the characters, in each subplot, are tied to the main plot that plays out on the world stage as the virus spreads and people perish.

An important variable for understanding viral spread and the movie is  R0 (pronounced: ‘R-nought’).  The spread of the virus is measured using R0, and referenced many times throughout the movie.  R0 is defined as the average number of new cases caused by one infectious person entering a totally susceptible population.  In other words.  The higher the R0 the more rapidly the virus spreads, and the more people die.  The R0 is finally figured out midway through the movie and is found to be double the R0 of the great influenza outbreak of 1918, which killed more than 50 million people worldwide.

Many scientist may frown upon the methods and examples in the film that describe virus epidemiology.  I however ignored the particulars and felt the director blended a decent amount of science fact in this fictional drama. Enough to provoke thought and concern among the general populous, which in itself makes this film worth seeing.