Humidity, school vacations connected to Mexico's flu waves during 2009 H1N1 pandemic
These factors account for the inconsistent regional timing of Mexico’s pandemic waves, which hit between regional humidity variations as well as school breaks.
The study was led by Dr. James Tamerius from the University of Iowa and Dr. Gerardo Chowell from Georgia State University. They used mathematical models to further understand the environmental and social processes that created two separate pandemic outbreaks or waves in Mexico during the fall and summer of 2009.
The summer wave was in Mexico’s tropical southeastern states. The larger fall wave was in the northern and central regions. The mathematical models connect high humidity levels with the fast spread of influenza throughout the tropical states, causing the early summer wave. Alternatively, moderate humidity levels slowed transmission of a pandemic wave before summer break in the northern and central regions.
Summer break decreased the transmission rate by approximately 14 percent. This delayed the pandemic wave that later hit the northern and central regions until the students attended school again in August.
These factors show why there were two separate pandemic waves for each region.
Further details are available in PLOS Computation Biology.