In recent years, multiple efforts have been made to predict and prevent the next pandemic and promote countries’ pandemic preparedness [23, 24]. The Global Health Security (GHS) Index, a comprehensive assessment of health security and related capabilities based on six categories (prevention, detection and reporting, response, health system, internal norm, and risk environment), scored countries to spur measurable changes in national health security and improve international capability to prepare for disease epidemic and pandemic outbreaks [16]. COVID-19, a highly contagious emerging infectious disease, rapidly evolved into a global pandemic two and a half months after its first reported case, increasing drastically both in the number of cases and deaths and in the number of countries reporting infections.
International travel is known to increase the risk of imported cases into countries and studies had assessed COVID-19 importation risk using international air travel data [10, 25]. However, other international movements (e.g., by land, sea, non-commercial air, goods) also contribute to importation risk. We used GCI, a broad global connectedness indicator, in our analysis and found that increased global connectedness was strongly correlated with faster spreading among countries with reported cases, with more rapid spread in Asia at the early stage of the pandemic, demonstrating that global connectedness and geographic location were significantly associated with the global spread of COVID-19.
While globalization indicator and location are distinct traits irrespective of pandemic activity, countries can improve capabilities to prevent, delay, detect, and respond to public health emergencies, as outlined in International Health Regulation [26]. In the context of the current pandemic, three months after the first reported cases, 38% of the “final” 24 countries reported in-country capacity to test for SARS-CoV-2, whereas most other countries exported or planned to export samples for testing. The limited COVID-19 testing in these countries likely affected their ability to timely detect and report newly imported or subsequent new domestic COVID-19 cases.
In addition to testing, active case-finding and surveillance systems are essential for detecting, monitoring, and curbing transmission of new outbreaks in a country. For COVID-19, WHO primarily recommended using existing ILI/SARI surveillance systems and reporting to GISRS platform [27] and such systems have been adopted by the U.S. and countries in Africa and Europe [28,29,30]. We examined the existing syndromic surveillance systems for influenza, ILI and SARI based on data reported to WHO Global Influenza Programme in the past 12 months and noted that 7 (29%) of the 24 countries did not report any influenza surveillance data to WHO. The lack of existing influenza surveillance systems in several countries may affect their ability to track new infections after arrival, which would subsequently affect their ability to develop effective and responsive infection prevention and control measures. In addition to influenza surveillances, other syndromic respiratory disease surveillance platforms or methods (e.g. event or community-based surveillance) could also be leveraged for COVID-19 surveillance to test and monitor community spread and detect signals of respiratory symptoms commonly associated with COVID-19. We could not determine the availability of surveillance and testing data from other national sources (e.g., country Ministry of Health).
Border control measures have been commonly used in past pandemics and epidemics to contain and slow the global spread of infectious diseases [11, 31]. For COVID-19, WHO had advised against the implementation of travel restrictions and border closures, because they may be ineffective, divert resources from other interventions, and have a negative impact on social, economic, and assistance activities [32]. The now-well-known asymptomatic and pre-symptomatic transmissions could further decrease the effectiveness of border control measures in preventing the introduction of COVID-19. A review found that entry screening measures had identified very low number of cases for the 2009 H1N1 Influenza Pandemic, 2014/2015 Ebola, and 2002/2003 SARS [33]. Despite the apparent ineffectiveness of border screening measures in identifying active cases, the study also summarized potential important concomitant positive effects, including discouraging ill persons from traveling, raising awareness and educating the traveling passengers, providing contacts of public health authorities to travelers in case they develop symptoms, collecting information for contact tracing, even though these impacts are difficult to evaluate [33].
For the COVID-19 pandemic, several studies have assessed the effectiveness of border measures and found that various border control measures, such as border closure and travel restrictions, had curbed regional or global spread of COVID-19, especially at the early stage of the pandemic [10, 34]. To assess the potential risk of imported cases, we calculated the annual per capita inbound visitor arrivals in the 24 countries using the most recent data reported in 2017 or 2018 [18]. Most of these countries may have a high risk of imported cases due to the volume of foreign visitor to many of the countries, particularly for the Pacific island nations, had they not taken any preemptive border control measures. All 24 countries under study had implemented at least two border control measures against the entry of COVID-19. Some enacted border measures (e.g., travel restrictions and border screenings) as early as January 2020, with more than half of the countries closing their air, land, and sea borders by the end of March. As the global spreading continued, 10 of 24 countries reported their first cases in April (8) and May 2020 (2), 4 reported near the end of 2020, and 10 countries had not reported any cases to WHO as of 18 February 2021. Although this study cannot directly evaluate the effectiveness of the specific measures, proactive implementation of border control measures likely contributed to slowing or preventing the infection across the borders, given the factors discussed above.
There is increasing evidence that asymptomatic and pre-symptomatic transmissions of COVID-19 played a key role in the initiation and acceleration of the outbreaks in other countries [35]. Therefore, while our analysis focused on delaying, detecting, and monitoring the importation of identified cases, it is equally vital for countries to prepare for the potentially undetected arrival of the disease. National strategies and designated task forces can guide and coordinate countries in implementing preparedness activities. The domestic control measures implemented by these 24 countries (e.g., preemptive banning of large gatherings and school or business closures) may have helped to curb the potential spread of undetected infections. Given the reported extreme burdens on healthcare resources and shortage of PPE in countries with widespread outbreaks, it is even more urgent for countries with limited capacity to carry out proactive preparedness activities, such as healthcare worker trainings, acquisition of additional PPE, and designation of local quarantine facilities.
The delay of disease introduction can provide countries a window of opportunity to prepare and implement preparedness strategies. In observing wide-spread transmission of COVID-19 in other countries, the global community accrued a substantial amount of knowledge on disease etiology, detection, treatment, and infection prevention and control measures. Less developed countries with fragile health systems can utilize the knowledge gained and resources shared by the global community through close collaborations and information sharing, to improve outbreak preparedness. To improve early detection, countries can increase in-country testing capacity, testing kits, equipment and supplies, laboratory capacity, and training. For timely and accurate monitoring, countries can improve surveillance capacity by utilizing and adapting existing surveillance systems and participating in international surveillance networks. Additionally, transparent information sharing, and effective communication and outreach, can all aid in the improvement of outbreak preparedness. Moreover, international coordination, as exemplified by the recently formed African Task Force for Coronavirus Preparedness and Response [36, 37], can substantially expand capacities, preparedness and responses on multiple workstreams, including laboratory diagnosis, surveillance, infection prevention and control, clinical treatment, risk communication, and supply chain and stockpile management. Lastly, the global situation continues to evolve despite the availability of COVID-19 vaccines. New challenges continue to emerge, such as the new variants [38, 39]. Therefore, it is essential for the global community to continue to improve and prioritize the capacities needed to prevent, detect, and respond, not only for COVID-19, but also for future global outbreaks.
Our analysis has several limitations. First, the analytic methods are largely observational and qualitative in nature. Therefore, this report cannot determine quantitatively the relative contributions from each factor and is not an evaluation of the effectiveness of such factors in delaying COVID-19 introduction. Nevertheless, the subsequent developments (e.g., significantly delayed introduction or COVID-free status a year after the pandemic declaration) indicated that proactive border measures, global connectiveness, and geographic aspect may be the main contributing factors. Second, data collection via broad web-based search may overlook relevant information, because of the search platforms used, vast amount of information, and/or language translation limitations. Third, we focused on the presence of ILI/SARI surveillance based on WHO’s recommendations and could not assess the availability of other surveillance platforms for the detection and surveillance of COVID-19 cases due to lack of public information. Lastly, potential non-reporting in selected countries can affect the findings and interpretation of data from those countries.