Background Emergency-use-authorization (EUA) is the representative biodefense policy that allows the use of unlicensed medical countermeasures or off-label use of approved medical countermeasures in response to public health emergencies. This article aims to determine why the EUA policies of the United States and South Korea produced drastically different outcomes during the COVID-19 pandemic, and how these outcomes were determined by the originations and evolutionary paths of the two policies. Method Historical institutionalism (HI) explains institutional changes—that is, how the institution is born and how it evolves—based on the concept of path dependency. However, the HI analytical narratives remain at the meso level of analysis in the context of structure and agency. This article discusses domestic and policy-level factors related to the origination of the biodefense institutions in the United States and South Korea using policy-learning concepts with the Event-related Policy Change Model. Results The 2001 anthrax letter attack (Amerithrax) and the 2015 Middle East Respiratory Syndrome (MERS) outbreak prompted the establishment of biodefense institutions in the United States and South Korea, respectively. Due to the different departure points and the mechanism of path dependency, the two countries’ EUAs evolved in different ways—the United States EUA reinforced the Post-Exposure Prophylaxis (PEP) function, while the South Korea EUA strengthened the Non-Pharmaceutical Intervention (NPI) function. Conclusions The evolution and outcomes of the two EUAs are different because both policies were born out of different needs. The United States EUA is primarily oriented toward protecting homeland security against CBRN (chemical, biological, radiological, and nuclear) threats, whereas the South Korea EUA is specifically designed for disease prevention against infectious disease outbreak.

The Emergency Use Authorization (EUA) policy, a representative biodefense policy, was legislated in the United States in 2001 based on lessons learned from Amerithrax, whereas Korea's EUA policy was based on lessons learned from the Middle East Respiratory Syndrome outbreak in 2015. Due to these divergent origins, the U.S. EUA's homeland security objectives were specialized to deal with highly pathogenic biological agents that could be exploited for bioterrorism, whereas the Korean EUA pursues disease containment purposes to strengthen mass-testing practices. During the early phase of the COVID-19 pandemic, the U.S. EUA revealed limitations in its integration with public health surveillance, laboratory partnerships, and insurance systems, which hampered the rapid expansion of testing capacities. Thereafter, once the limitations of the EUA were circumvented, the testing capacity of the United States began to catch up with that of South Korea, and later skyrocketed after solving these issues.

Background: Historical institutionalism (HI) determines that institutions have been transformed by a pattern of punctuated evolution due to exogenous shocks. Although scholars frequently emphasize the role of agency - endogenous factors – when it comes to institutional changes, but the HI analytic narratives still remain in the meso-level analysis in the context of structure and agency. This article provides domestic and policy-level accounts of where biodefense institutions of the United States and South Korea come from, seeing through emergency-use-authorization (EUA) policy, and how the EUA policies have evolved by employing the policy-learning concepts through the Event-related Policy Change Model. Results: By employing the Birkland’s model, this article complements the limitation of the meso-level analysis in addressing that the 2001 Amerithrax and the 2015 Middle East Respiratory Syndrome (MERS) outbreak rooted originations and purposes of the biodefense respectively. Since the crisis, a new post-crisis agenda in society contributed to establishing new domestic coalition, which begin to act as endogenous driving forces that institutionalize new biodefense institutions and even reinforce them through path dependent way when the institutions evolved. Therefore, EUA policy cores (Post-Exposure Prophylaxis (PEP) in the United States and Non-Pharmaceutical Intervention (NPI) in South Korea keep strengthened during the policy revisions. Conclusions: The United States and South Korea have different originations and purposes of biodefense, which are institutions evolving through self-reinforce dependent way based on the lessons learned from past crises. In sum, under the homeland security biodefense institution, the US EUA focuses on the development of specialized, unlicensed PEP in response to public health emergencies; on the other hand, under the disease containment-centric biodefense institution, the Korean EUA is specialized to conduct NPI missions in response to public health emergencies.

In South Korea, COVID-19 pandemic responses, namely the 3T (testing, tracing, and treating) strategy, emerged as a new biosurveillance regime actively using new information technology (IT) and digital tools. The foundation of the Korean 3T system is epidemiological investigation efforts and clinical practices exploiting the use of new digital and IT tools. Due to these unique features, the Korean 3T system can be referred to as a “contact-based biosurveillance system,” which is an advanced version of the traditional biosurveillance models (indicator-based or event-based models). This article illustrates how the contact-based biosurveillance system originated from the experience with the 2015 Middle East Respiratory Syndrome (MERS) outbreak. The post-MERS Korean biosurveillance regime actively adopted the utility of new digital and IT tools to strengthen not only the ex-ante epidemic intelligence capabilities (by traditional models) but also the ex-post response and recovery capabilities (digital contact tracing and digital health intervention). However, critics claim that the Korean 3T system may violate individuals’ privacy and human rights by addressing the fact that the Korean biosurveillance system would strengthen social surveillance and population control by the government as a “digital big brother” in the cyber age. Nevertheless, 3T biosurveillance promises a positive future direction for digital health practice in the current biosurveillance regimes.

UNSTRUCTURED South Korea COVID-19 pandemic responses, namely the 3T (testing, tracing, and treating) strategy, come to the fore as a new biosurveillance regime utilizing new IT and digital tools actively. The 3T biosurveillance system is a developed version of the traditional biosurveillance systems (indicator-based or event-based systems), which can provide epidemic intelligence capabilities for both ex ante prevention/preparedness or ex post response/recovery missions. Epidemiological investigation efforts exploiting the use of new digital and IT tools are the ground of the Korean 3T system practicing test, trace, and treatment mission, which can be referred to as ‘contact-based biosurveillance system.’ However, critics argue that the Korea’s 3T strategy may violate individuals’ privacy and human rights in addressing that the Korean biosurveillance system would strengthen the social surveillance and population control by the government as a “digital big brother” in the cyber age. However, closer scrutiny reveals that the Korea’s digital-based biosurveillance system for pandemic response has evolved since the experience of the 2015 Middle East Respiratory Syndrome (MERS) outbreak, by citizen’s requests and self-help behaviors