In late February 2003, a man, who had recently travelled to China, presented to a hospital in Hanoi with what an astute clinician recognised as an unusual, severe acute respiratory syndrome (which would come to be known as SARS). At about the same time, the Chinese Ministry of Health announced, belatedly, that an outbreak of severe atypical pneumonia in Guangdong province had already claimed at least 300 lives, since November 2002. Scientists and epidemiologists, from WHO’s Global Influenza Surveillance (GISN) and Global Outbreak and Response (GOARN) networks, immediately began collecting and analysing microbiological, clinical and epidemiological data. By mid-March, another 150 suspected cases of SARS had been identified in Hong Kong, Singapore, Vietnam and Canada (Heymann and Rodier 2004). Despite China’s delayed outbreak report, a massive global effort, led by WHO and GOARN, rapidly identified a novel coronavirus (SARS CoV) as the cause. They documented modes of transmission, nosocomial infections, risk factors and a high mortality, which enabled WHO to develop evidence-based guidance for diagnosis, management, hospital infection control, quarantine and travel. Within 6 months, the global spread of SARS had ceased, albeit only after it had spread to 29 countries on six continents, caused 8437 cases (of which 92% were in China) and 813 deaths, and cost the global economy an estimated US$54 billion (Knobler et al. 2004). Similar delays in recognition and reporting of the 2013–2014 Ebola virus disease outbreak in West Africa led to unprecedented cross-border transmission and, ultimately, > 28,000 cases and 11,000 deaths—mostly in the three affected countries—before it was eventually brought under control by a massive, coordinated international effort (Koch 2016a).