DISCUSSION

We found that the pandemic situation of COVID-19 varied widely in the Western Pacific Region. Asian countries close to the epicenter of the outbreak have seen earlier cases of infection, which is consistent with the transmission pattern of SARS-CoV-2, that is, relatively frequent interpersonal interactions in the early stages of the pandemic contributed to the prevalence of COVID-19. ^{Reference Wang, Hu and Hu5,Reference Chen, Zhou and Dong6}

Although the number of new cases seems to have leveled off across the Western Pacific Region, which may due to the timely strict measures, the suppressed infection growth rate in heavily infected countries, such as China and South Korea (Figure 2), does not indicate that transmission in these areas has been blocked. In particular, the number of reported infections is still growing in the Western Pacific islands (Figure 2). Compared with other countries in this region, there is a significant lag in the onset time of initial infected cases in these islands, possibly reflecting the remote location of and inconvenient transportation to Western Pacific Islands.

Meanwhile, there was no marked increase for a while after the first infection in many countries (Figure 2g-j), but eventually a significant increase broke out over time. This finding further proves that COVID-19 has a long incubation period and insidious initial symptoms as we described previously, ^{Reference Chen, Hu and Zhang7} which makes the disease difficult to diagnose in patients with early infection. Therefore, in cases where nucleic acid detection methods are not yet universally available, Western Pacific Islands need to be particularly vigilant for patients’ initial symptoms for COVID-19 screening.

The Western Pacific Region is home to almost 1.9 billion people across 37 countries and areas. Our previous findings suggest that the inadequate capacity to respond to public emergencies caused by an uneven distribution of medical resources is a crucial factor contributing to the unsatisfactory outcome of COVID-19 in less-developed regions. ^{Reference Hu, Zhang and Wang8} Compared with developed areas, countries or territories in the Western Pacific Region have insufficient health-care resources, and relatively low detection and prevention capacity. ^{Reference Kandel, Chungong and Omaar4} Although these countries or territories have just a few confirmed infected people, without adequate control and preparedness, large-scale community transmission of COVID-19 is likely to occur. Fortunately, countries such as Fiji have already started to monitor high-risk persons and strengthen the management of international borders. ⁹ Given that COVID-19 does not have a high CFR if the medical system is not overloaded, ^{Reference Niforatos, Melnick and Faust10} it is necessary to close or strictly control the external traffic into the area and prepare adequate quarantine sites and mobile hospitals in the Western Pacific Islands to avoid a surge of patients. In addition, it is extremely important to publicize and popularize COVID-19 prevention methods, possible psychological interventions pertinent to the population exposed to the crisis, and timely disclosure of information.

The Western Pacific Islands have long been considered one of the most environmentally vulnerable regions in the world. On the one hand, the special geographical environment, such as the extreme El Nino climate, makes it difficult to establish an unbreakable health system. ^{Reference Filho, Scheday and Boenecke11} Furthermore, the less-developed economy and limited management capacity present additional challenges for the population to withstand an infectious disease pandemic. Economic globalization, trade, and population mobility have exacerbated the challenges of infectious disease control. Commercial and trade facilities allow infectious diseases to quickly cross the political borders of sovereign states, leading to the global spread of diseases. Due to the discontinuity between lands in the Western Pacific Island countries and territories, the extensive networks of frequent population mobility here also facilitate the spread of infectious diseases. ^{Reference Craig, Heywood and Hall12,Reference Xu, Lau and Zhou13} Previous studies have confirmed that infectious diseases depopulated isolated Pacific islands when they were first exposed to global pathogen spread. ^{Reference Shanks14} Fortunately, a Pacific Syndromic Surveillance System (PSSS) has been established for early warning of infectious diseases. ^{Reference Paterson, Kool and Durrheim15,Reference Kool, Paterson and Pavlin16} It is an urgent need to further improve and scientifically enable this system to inhibit the spread of COVID-19 in this special period.

In conclusion, public health crises such as COVID-19 are challenges for all mankind. The shortcomings of public health-care capacities exposed by the outbreak also highlight the urgency of strengthening control in the Western Pacific Islands.