Delays in Global Disease Outbreak Responses: Lessons From H1N1, Ebola, and Zika

Steven J. Hoffman, JD, PhD, LLD; Sarah L. Silverberg, BArtsSc


Am J Public Health. 2018;108(3):329-333. 

In This Article

Abstract and Introduction


In global disease outbreaks, there are significant time delays between the source of an outbreak and collective action. Some delay is necessary, but recent delays have been extended by insufficient surveillance capacity and time-consuming efforts to mobilize action.

Three public health emergencies of international concern (PHEICs)—H1N1, Ebola, and Zika—allow us to identify and compare sources of delays and consider seven hypotheses about what influences the length of delays. These hypotheses can then motivate further research that empirically tests them. The three PHEICs suggest that deferred global mobilization is a greater source of delay than is poor surveillance capacity. These case study outbreaks support hypotheses that we see quicker responses for novel diseases when outbreaks do not coincide with holidays and when US citizens are infected. They do not support hypotheses that we see quicker responses for more severe outbreaks or those that threaten larger numbers of people.

Better understanding the reason for delays can help target policy interventions and identify the kind of global institutional changes needed to reduce the spread and severity of future PHEICs.


Increasing global trade, travel, and climate change have accelerated the spread of disease outbreaks beyond national borders to more quickly develop into international concerns. After the severe acute respiratory syndrome (SARS) epidemic, there were major efforts to build surveillance and response systems to identify outbreaks early, respond globally, and contain spread at the source.[1]

Yet despite these efforts, we still see prolonged time delays in severe outbreaks between their emergence and global collective action. To simplify, there are two main processes that can result in delays. First, there will be a delay between the emergence of an outbreak's index case and the detection of the outbreak by health care providers, laboratories, and public health authorities. One goal of disease surveillance is to minimize this delay and maximize available information for guiding the public health response through ongoing data collection, analysis, and management. Second, there will be a delay between an outbreak's detection and widespread recognition of the outbreak as an international concern. Should outbreaks involve international spread and require a coordinated international response, such recognition is best evidenced by a declaration from the World Health Organization (WHO) that it constitutes a public health emergency of international concern (PHEIC). In making this declaration, WHO's director general considers the prevention, protection, and response needs of the situation and the advice of an emergency committee before potentially mobilizing efforts to address these needs.[2]

When the systems for recognizing and responding to disease outbreaks act too slowly, the result is unnecessary delay, greater disease spread, additional people affected, and more lives lost.[3–6] We used the last three PHEICs—H1N1, Ebola, and Zika outbreaks—as case studies to compare sources of delays and to screen seven potential hypotheses of what influences the length of delays. Our goal was to identify and consider possible reasons for the delays to motivate future hypothesis-testing research that empirically assesses them and ultimately informs the design of evidence-based interventions that hasten future outbreak responses.