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 Calderón invoked the emergency health powers outlined in Mexico's Constitution and General Health Law.^{1 - 2} 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.^{3 - 7} As Ignacio Villaseñor 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 précis of our impressions.

Vested with executive authority to act for the president during the crisis, Mexico's Health Secretary José Ángel Córdova, MD, served as the only governmental spokesman at the height of the outbreak, delivering consistent information in accordance with regularly updated epidemiological and clinical data.⁸ He invited stakeholders from key arenas of health, government, media, and education literally to share the stage with him at daily, sometimes hourly, press briefings. Many Mexican health experts referred to this model of communication as one in which sources and messages were strictly aligned to avoid public confusion.

Mexico's Health Promotion department worked tirelessly to disseminate a wide array of public health pamphlets and posters to inhabitants in 31 states and the national capital. These materials relied greatly on visual representations given Mexico's heterogeneous population and uneven literacy rates. They appear to have positively influenced social behavior. Additionally, the national media, including television, radio, and print, collaborated well with Health Promotion to educate citizens on personal hygiene techniques.

Mexican health officials demonstrated great finesse as they interpreted the phenomenon of citizens wearing facemasks, a measure not included in the initial governmental NPI guidelines. Dr Lucero Rodríguez Cabrera of Health Promotion described this as the “spontaneous response of the population to protect themselves,” further adding that this social behavior prompted the real-time development of public health literature about the “correct use and disposal of face masks.”

The general consensus is that Mexicans implemented NPIs willingly and with little pushback. There are strong indications that this may have been related to Mexico's multisector approach to health crises, which seeks to involve citizens based on various social, occupational, and geographical characteristics. As Miguel Ángel Lezana, MD, Director of the National Center for Epidemiological Surveillance and Disease Prevention, told us in an interview, “it was most impressive how people adopted the guidelines.”

Remarkably, concern for health protection transcended partisan politics at least temporarily. Indeed, during the crisis the fractious rift between the Partido de la Revolución Democrática (PRD), which governs Mexico City, and the president's party, the Partido Acción Nacional (PAN), was attenuated. As President Calderón stated at an international summit on A(H1N1) held in Cancún in early July 2009, “We sought at all times to protect the health of Mexicans; this was our priority above any political, economic, or other consideration.”⁹ Mexico City's health department concurred, as Dr Villaseñor Ruiz emphatically told us, “Public health superseded politics.”

Epidemiological surveillance and case reporting were inconsistent and incomplete across the country.¹⁰ While some states have computerized systems that gather critical morbidity and mortality data on a standardized basis and transmit it to federal agencies, a few states still use pen and paper, and several did not generate any case data. These lacunae as well as other technological barriers led to an early gross overestimation of case-fatality rates. Some of the preliminary numbers indicated mortality rates higher than the devastating 1918 influenza pandemic and were instrumental in compelling Mexico's bold response.

Mexico did not have a viral library available to conduct rapid genomic identification of novel influenza strains. Thus, precious time was wasted waiting for the analysis of samples that were sent, on the Mexican presidential plane no less, to Canada's National Microbiology Laboratory and the US Centers for Disease Control and Prevention.

Even with excellent public health risk communications, some segments of the population were not reached. In mid-May, Mexico's Health Promotion department conducted surveys that are providing critical insights about how to expand or revise messaging. Specifically, these studies found that sneeze etiquette among many Mexicans is poor and that personal hygiene recommendations were not reaching teenagers, a potentially high-risk demographic for A(H1N1) infection.

The economic costs were enormous. Because of the pandemic crisis, economists project that Mexico's Gross Domestic Product is likely to decrease between 0.5% and 1% more than already expected in a gloomy economy.¹⁰ One estimate calculated that by mid-May the epidemic had cost Mexico $2.3 billion dollars.⁸ A few states had disproportionate economic losses such as Quintana Roo, home to the tourist destination of Cancún, where hotel occupancy rates dropped from 95% to less than 10% overnight.

The likelihood of reinstituting the same menu of NPIs in Mexico in the fall is small, so health officials there are focusing on how to recalibrate NPIs to different communities while matching these responses to the severity of the circulating virus, in concert with the distribution of antivirals and potentially vaccines. Concerned with the risks of epidemic fatigue and poor social compliance, Dr Lezana told us, “We have to refine mitigation strategies in a second wave because people become desensitized, this is a great challenge.”

Much remains to be learned from the data being gathered on Mexico's public health experiment with nonpharmaceutical interventions. In the months to come, a raft of studies can be expected to better determine the efficacy and costs of NPIs. Perhaps the most immediately valuable lesson learned from spring 2009 is that Mexico's transparency and rapid response not only helped other countries react properly but also set a high bar for how the 21st-century global community must cooperate to share information about impending epidemics.