What Mexico taught the world about pandemic influenza preparedness and community mitigation strategies.

ON APRIL 24, 2009, FOR THE FIRST TIME IN MEXIcan history, President Felipe Calderon invoked the emergency health powers outlined in Mexico’s Constitution and General Health Law. The catalyst for this dramatic action was the appearance of a novel strain of influenza A(H1N1) of unclear severity. Harkening back to measures that originated in the late 14th century, when bubonic plague stalked much of Europe and Asia prompting ports and nation-states to order mass quarantines, Mexico instituted a broad-based and exacting menu of community mitigation strategies, or nonpharmaceutical interventions (NPIs), including school closure, public gathering bans, isolation, quarantine, and social distancing. Beginning on the morning of April 24, all schools were closed in Mexico City, the world’s third largest metropolis (population 20 million), which encompasses the federal district and state of Mexico. By April 27, authorities cast the net wider and all Mexicans awoke to shuttered schools, emptied restaurants, a steady stream of personal hygiene messages, and sporting events closed to spectators but broadcast on national television. For the next 2 weeks, Mexico came to a virtual standstill. The foundation of Mexico’s response is an increasing body of historical, epidemiological, and modeling data demonstrating statistically significant associations between the early, layered, and sustained implementation of NPIs and a reduction in peak mortality rate, the time to reach peak mortality, and the cumulative mortality burden from influenza. As Ignacio Villasenor Ruiz, MD of Mexico City’s health department told us in a recent interview, “[We] had to recognize that influenza transmission could not be stopped, but we could do two things” using community mitigation strategies, “first, slow the transmission rate and second, lower mortality.” The prevailing perception among international health experts is that Mexico responded swiftly, transparently, and efficaciously to mitigate the spread of influenza. However, these actions carried high social, political, and economic costs. The critical question to ask, as nations and communities consider applying such disruptive measures this coming fall, is what successes, problems, and lessons for the future can be gleaned from what many Mexicans consider a watershed in public health. To capture a historical snapshot of these events, we traveled to Mexico in early July 2009 and interviewed dozens of Mexican citizens and public officials. The following is a precis of our impressions.