Practice of Public Health Interventions Collaboration and Integrated in Macau SAR and Zhuhai to Response to Pandemic of COVID-19


 BackgroundIn 2020, the Guangdong-Hong Kong-Macau Greater Bay Area (GBA) was in proximity to the second epicenter of COVID-19 in China, where Macau and Zhuhai are located. Both cities communicated, cooperated, and coordinated under different backgrounds to play a "cocity" effect in response to the COVID-19 pandemic.ResultsIn 2020, Macau and Zhuhai had a total of 46 and 112 confirmed cases of COVID-19, respectively. Ten and 98 confirmed cases in two cities that were imported from mainland China or were the result of local infection caused by imported cases of patients who recovered and were discharged during the first period (January 1 to March 14), respectively. During the second period (March 15 to December 31), both of the cities mainly disposed of imported cases (36 and 14 cases in Macau and Zhuhai) from abroad. In the third period (July 15 to December 31), the two cities gradually returned to normal work and life and economic recovery. Under dynamically adjusted prevention and control measures, the two cities have adopted a series of border control measures based on domestic and abroad changes in the COVID-19 epidemic situation. They had closely cooperated and shared information in terms of epidemic information docking, traffic control, patient care, and material guarantees. The prevention and control policies and measures are basically the same in the two cities and different in the 3 time periods. Health QR code exchange was the basis of mobility of residents between the two cities.ConclusionsBoth cities had zero tolerance for COVID-19 cases and adopted a suppression strategy to accurately grasp the changing epidemic situation at any time. There was no community transmission of local cases, and the control effect with resumption of work and personnel turnover was very obvious in the two cities. These characteristics provide a suitable example for other countries and cities to better understand the effectiveness of control measures to address the possible long-term existence of COVID-19.


Abstract Background
In 2020, the Guangdong-Hong Kong-Macau Greater Bay Area (GBA) was in proximity to the second epicenter of COVID-19 in China, where Macau and Zhuhai are located. Both cities communicated, cooperated, and coordinated under different backgrounds to play a "cocity" effect in response to the COVID-19 pandemic.

Results
In 2020, Macau and Zhuhai had a total of 46 and 112 con rmed cases of COVID-19, respectively. Ten and 98 con rmed cases in two cities that were imported from mainland China or were the result of local infection caused by imported cases of patients who recovered and were discharged during the rst period (January 1 to March 14), respectively. During the second period (March 15 to December 31), both of the cities mainly disposed of imported cases (36 and 14 cases in Macau and Zhuhai) from abroad. In the third period (July 15 to December 31), the two cities gradually returned to normal work and life and economic recovery. Under dynamically adjusted prevention and control measures, the two cities have adopted a series of border control measures based on domestic and abroad changes in the COVID-19 epidemic situation. They had closely cooperated and shared information in terms of epidemic information docking, tra c control, patient care, and material guarantees. The prevention and control policies and measures are basically the same in the two cities and different in the 3 time periods. Health QR code exchange was the basis of mobility of residents between the two cities.

Conclusions
Both cities had zero tolerance for COVID-19 cases and adopted a suppression strategy to accurately grasp the changing epidemic situation at any time. There was no community transmission of local cases, and the control effect with resumption of work and personnel turnover was very obvious in the two cities.
These characteristics provide a suitable example for other countries and cities to better understand the effectiveness of control measures to address the possible long-term existence of COVID-19.

Background
Coronavirus disease 2019 (COVID-19) has continued since the World Health Organization (WHO) announced a COVID-19 pandemic in March 2020. 1 The pandemic has brought a huge burden of disease to the world and has seriously affected the economic development of society and people's normal lives. 2,3 Hubei Province (especially Wuhan), where the rst case was found, had the largest number of con rmed cases of COVID-19 in China 4 , followed by the Guangdong-Hong Kong-Macau Greater Bay Area (GBA), which was the fourth largest bay area in the world and has a population of 71 million in proximity to the second epicenter where Macau SAR (Macau) and Zhuhai City are located.
Macau is a special administrative region of China. The Chinese government resumed the exercise of sovereignty over Macau 20 years ago. Macau is a successful practice of China's "One Country, Two Political Systems" (Mainland China implements a socialist system, and Macau implements a capitalist system). Macau is connected to Zhuhai, which is attached to Guangdong Province and one of the major frontier cities in the process of China's globalization by land to land, and the two cities have close population ows with each other. Some ports are set up to facilitate 24-hour customs clearance and reach a 1-hour living circle between the two cities, and approximately 24 million passengers entered Macau from Zhuhai in 2019.
Macau and Zhuhai are famous ports and tourist cities where they are located and are facing greater import pressure from the COVID-19 pandemic. During the response to the COVID-19 pandemic, Macau and Zhuhai communicated, cooperated, and coordinated under different frameworks to have a "cocity" effect. For example, ghting together during the imported outbreak, digesting the infected cases that were linked between the two cities, consensus on zero tolerance for COVID-19 cases, economic recovery under normalized prevention and control measures, minimizing the impact of this global pandemic, abandoning different political systems and launching cooperation and integration as the cocity. All these efforts under nonpharmaceutical interventions have been successfully practiced during the COVID-19 pandemic with a background fatality rate of 2.7%-5% 5,6 with a large number of infected patients being at risk of impacting the medical system, and no vaccine available. To date, there are no reports on antiepidemic collaboration as a cocity under different backgrounds. These characteristics provide a suitable example for researchers and decision makers in countries and cities severely affected by the COVID-19 pandemic to better understand the effectiveness of control measures to address the possible long-term existence of COVID- 19. 7 Results Epidemiological characteristics of COVID-19 outbreaks in Macau and Zhuhai In 2020, Macau had a total of 46 con rmed cases of COVID-19. Seven cases were Wuhan-related cases, and 1 case did not have a history of living in Wuhan but had a history of travel to the hospital of Zhuhai.
Two cases were potentially local infections, and one of them had a contact history with imported cases, but another source of infection was unclear 8 , and 36 cases had a travel history abroad.
A total of 112 con rmed cases were reported in Zhuhai in 2020, of which 14 (12.5%) were locally infected, 84 (75.0%) were imported domestically (79 cases were Wuhan-related cases or related to cities around Wuhan, 3 cases had a history of living in other cities and 2 cases were infected on a cruise ship), and 14 (12.5%) were imported from outside mainland China, including foreign countries (10 cases) and Hong Kong S.A.R. (4 cases). (Figure 2). Of the 112 cases, 25 cases (22.3%) had travel (20 cases), passing-by (3 cases) or work (2 cases) histories in Macau during the incubation period. Among them, 12 cases only entered and exited from Gongbei port, 12 cases passed from Gongbei and Hengqin ports, and 1 case migrated from Cross-border industrial zone port.

Characteristics of 3 Time Periods
Within the rst period (January 1 to March 14), the rst con rmed case of COVID-19 was reported on January 22 in Macau, and no new cases continued for 39 days after the 10 th con rmed case was reported on February 4. Similarly, the rst con rmed case was reported on January 20 in Zhuhai, and no new cases increased for 30 days after the 98th con rmed case was reported on February 17. All con rmed cases that were imported from mainland domestically or local infections caused by imported cases in two cities recovered and were discharged before March 14.  Iran and other countries in the 14 days before entry, including Macau residents, tourists and foreign employees, were required to undergo intensive 14-day medical observation. Border control 4. All nonlocal residents who had been to a foreign country within 14 days before entry were prohibited from entering. All persons who have been to the Hong Kong S.A.R. or Taiwan within 14 days before entry must undergo 14 days of intensive medical observation. Border control 5. Centralized quarantine medical observations will not be implemented for out-of-town employees who live in Zhuhai City. All persons entering Macau from mainland China must hold a 7-day virus nucleic acid test certi cate, which can be displayed by the Health QR Code. Border control 6. All persons entering Macau from Hong Kong must have a certi cate of a negative nucleic acid test for the novel coronavirus within 72 hours and must undergo 14 days of intensive medical observation. Starting on August 4, according to the changing patterns of the epidemic in some cities in mainland China, , people who have been to Dalian, Urumqi, Qingdao and other cities within 14 days before entering must undergo 14 days of intensive medical observation. After the partial epidemic was over, relevant quarantine measures were cancelled. Border control 7. Those entering Macau from Hong Kong must have a negative nucleic acid test certi cate within 24 hours and receive 14 days of medical observation. Border control 8. For those who had been to a country or region outside mainland China for the past 14 days, the medical observation period for isolation in Macau increased from 14 days to 21 days.
Zhuhai:Border control 1. Zhuhai Airport conducted temperature testing on passengers from Wuhan. Border control 2. All ports in Zhuhai have launched a health declaration system for entry-exit persons. Border control 3. Suspension of endorsement for free travel from mainland China to Macau.
Border control 4. A comprehensive nucleic acid test for high-risk populations from Hubei Province (especially Wuhan City) to Zhuhai was conducted and required these high-risk people to stay at home for 14 days. Border control 5. People who came to Zhuhai from high-risk areas in other cities of mainland China needed to be quarantined for 14 days. Border control 6. People from outside of mainland China, including foreign countries, Macau and Hong Kong, needed to be quarantined for 14 days, except for those specially exempted. Border control 7. All personnel coming from Macau to Zhuhai were not quarantined for 14 days, and the scope of activities was limited to 9 cities in Guangdong Province. Border control 8. The scope of activities for people coming from Macau to Zhuhai was expanded to Guangdong Province. After 14 days, they could move nationwide if the nucleic acid test result was negative. Border control 9. Gradually resume processing of visas for residents of Zhuhai City, residents of Guangdong Province, and all mainland residents to travel to Macau. People can pass freely with the negative certi cate of nucleic acid within 7 days, and the "green code" logo interchangeable between Macau or Guangdong Health QR Code.

Matrix of main strategies and measures in 3 Time Periods
The two cities have adopted a series of border control measures based on the changes of the COVID-19 epidemic situation of domestic and abroad. They had closely cooperated and shared information in terms of epidemic information docking, tra c control, patient care, and material guarantees. The prevention and control policies and measures are basically the same in the two cities ( Figure 1 and Table   1). 2.The governments of the two cities communicated and cooperated as soon as possible to mobilize the whole society.
3.Docking of professional technical institutions for disease control, port quarantine institutions, etc., to exchange and sharing epidemic information.
4.Actively control the spread of import cases and local cases. 5.Under the premise that the epidemic is gradually within control, to increase the communication between the two cities step by step, and to promote cocity operation and economic recovery.
Source of infection controled 1.Port of entry to implement health declaration and dynamically adjusted border control strategies.
2.Timely diagnosis and treatment of con rmed or suspected cases, strict discharge standards, and isolation observation and followup after discharge.
3. Strictly follow up close contacts and give centralized isolation for medical observation (This measure extended to close contacts of close contacts later). 4. Strengthen the monitoring of fever clinics, and the screening of patients by medical institutions, and prevent iatrogenic infection. Strengthen the sensitivity and timeliness of suspicious cases of infection detection, and strengthen multichannel early warning. symptoms on the day, 14 days of contact history, 14 days of travel history). The travelers could pass the port with the green code after completion. According to changes in epidemic prevention and control or personal situations, the three-color code (red, yellow, and green) assignment rules of the "Health QR Code" were dynamically adjusted and improved ( Figure 2).

Discussion
Government deployment and zero tolerance consensus against COVID-19 between two cities with different frameworks.
Although Macau and Zhuhai belong to the same country, there are several differences in the political systems, legal regulations, and procedures between the two cities. Since the outbreak of COVID-19 in Wuhan, the governments of Macau and Zhuhai have attached great importance and responded quickly.
Unlike other cities or countries, such as mitigation strategies 9 10 , which aim to slow the spread of COVID-19 in the community and prevent the intensive care unit (ICU) from being unstoppable when dealing with severe cases, Macau and Zhuhai have zero tolerance for COVID-19 cases and adopt suppression strategies to accurately grasp the changing epidemic situation at any time. Under a strong coordination mechanism, the two cities connected closely together, convened multiple emergency meetings as soon as possible, implemented a daily timing and mutual feedback noti cation system, and discussed and shared the latest epidemic information and control decisions in a timely manner. The prevention and control of the COVID-19 epidemic had achieved positive results, and the resumption of work, production and school education had been effective. Since the COVID-19 pandemic, there has not been such thorough cooperation between two cities. Sharing successful experiences can be used as a reference for cooperation between other areas, regions or countries. 11 There was no cross-cultural consensus on whether wearing a mask was a physical intervention method to effectively prevent the spread of diseases. 12 However, residents in Macau and Zhuhai had uni ed support for wearing masks based on extensive publicity, education and promotion in the early stage of the COVID-19 outbreak. When there was a high degree of compliance, wearing masks was the most effective way to reduce the spread of the virus. 13,14 The governments of two cities established a riskadjusted mask use strategy, scienti cally promoted the use of masks, ensured an adequate supply of masks, and cooperated to reduce the unfairness of health resources.
Necessary conditions of response to the COVID-19 pandemic in Macau and Zhuhai gradually reached the cocity.
Macau and Zhuhai, which are geographically adjacent and both tourist and port cities in the GBA, had many similarities in the pressure of the global pandemic. The occurrence and development of the COVID-19 epidemic in Macau and Zhuhai were highly consistent. They processed cases imported mainly from Hubei in the early stage, and in the later stage, they faced cases imported mainly from foreign countries or Hong Kong in China. Macau and Zhuhai strictly implemented management measures for their respective con rmed cases, suspected cases and close contacts and actively dealt with related cases traveling or working between the two cities. The local cases that were all epidemiologically related to imported cases were less than 20% in both cities; speci cally, there were no community spreads.
The prevention and control measures for high-risk people in Macau and Zhuhai were highly consistent. Nonpharmacological interventions, which included avoiding mass gatherings, school closures, case isolation, contact tracing 15 , and implementation of infection prevention strategies in medical institutions, were all means to interrupt the pandemic. 16,17 During the rst period, both cities implemented strict health quarantine and isolated medical observation for those who had lived in Hubei in the previous 14 days. 18 The timeliness of strategies was very important to address the forms of epidemics in different situations, and timely dynamic adjustments must be made to respond consistently. Starting from the second period when the epidemic situation in mainland China had been well controlled, they shifted to closed management of the entire chain from entry territory to free immigration regardless of nationality and comprehensively strengthening the prevention of foreign or Hong Kong of China imports. Residents from mainland China gradually were not included in the scope of immigration control in the third period. The exchange of the itinerary trajectory of the con rmed cases, close contact tracking information and other information related to epidemic prevention and control. At the same time, mutual recognition of medical isolation measures was implemented for personnel traveling between Zhuhai and Macau.
Efforts to achieve a response to the COVID-19 pandemic as a cocity The COVID-19 pandemic caused governments to scramble to reduce their vulnerability to the virus by restricting global trade and the movement of people. 19 However, with the closure of borders and the implementation of strict immigration measures, there has been a major disruption in the global supply chain, which has adversely affected employment and poverty. In the long run, strict social distancing measures and long-term lockdown suppression interventions to address the COVID-19 pandemic were unsustainable. These long-term measures would have a signi cant adverse effect on the economy and health welfare. 20 Both Macau and Zhuhai are tourist cities with extremely large population ows. Especially for cities that rely on export-oriented economies, it is necessary to consider the balance between social protection plans and epidemic control. Cooperation between the two cities was limited not only to epidemic control but also to basic living security and economic recovery promotion. For example, for cross-border truck drivers, students, etc., exempt quarantine measures, adjustment of strategies in a timely manner based on Health QR Code 21 intercommunication and nucleic acid testing to gradually open tourism and promote consumption, and continue to conduct strict disease monitoring. The common goal of both was to gradually balance the economic and health consequences, that is, "safe reopening" 22 , and this effect was gradually re ected.
The COVID-19 pandemic brought severe challenges and provided an opportunity for cooperation between the governments of two cities. Working closely with public health policy experts and medical experts, feasible and dynamic adjustment plans were designed. 23 Both cities have gradually reached 100% foreign immigrants to implement centralized quarantine and medical observation, 100% nucleic acid testing for travelers of entry, and 100% health code mutual recognition management. The measures were implemented in phases. From providing ordinary citizens with free nucleic acid testing services, implementing mutual recognition of health codes, and gradually expanding those exempted from quarantine, the policy for mainland tourists to Macau was gradually relaxed. After consultation and consensus, the "cocity management" of epidemic prevention and control could be implemented.
Health QR code conversion was the basis of the mobility of residents The Health QR code generated using the mobile application was based on the user's activity in the previous 14 days, including whether the user had been to a high-risk area and whether he had been in contact with a con rmed or suspected case. 24 According to the speci c circumstances involved in epidemic risk and the classi cation requirements of prohibition, restriction, and normal ow, corresponding management measures should be taken for people with different color codes. The use and intercommunication of the Health QR Code of the two cities indicated that their respective departments of health, public security, communications management, customs, border inspection, transportation and other departments should rely on a uni ed public data platform to strengthen the timely sharing of epidemic-related data. Comprehensive analysis was carried out to ensure accurate coding, and at the same time, the dynamic adjustment of the "health code" coding rules must be consistent between two cities and provide convenience for the elderly and minors to use the "health code". 25 It was much more time-e cient to show the QR code when required. It has also helped to facilitate tra c and speed up the resumption of work and production, ultimately promoting regional economic recovery.

Movement trajectory of cross-border exemption of quarantined people and truck drivers or management of oating shermen
For a period of time in the rst stage, Macau prohibited all nonlocal residents from entering the territory, except for some mainland Chinese employees whose regular nucleic acid monitoring was carried out.
With the gradual resumption of school, students and teachers who live in Zhuhai and attend schools in Macau were also exempted. Zhuhai also implemented quarantine exemptions for certain people.
Exempting people from quarantine increased import risk 26 , but strict management of the trajectory of actions provided the possibility for necessary work and life.
Cross-border truck drivers, including those from Macau or Hong Kong, were registered and managed. The trucks were equipped with a positioning system and carried out point-to-point transportation from the port of entry to the destination factory (warehouse) according to the declared activity track and did not travel to areas outside the declaration. The tra c node service stations were equipped with a special parking lot, rest area, and toilet for cross-border truck drivers, which scanned QR codes and implemented closed management. Cross-border truck drivers should hold a valid nucleic acid test certi cate within 48 or 72 hours of cross-border activities and conduct regular nucleic acid tests.
As the pandemic progressed, disease control responses had become more detailed and targeted. Understanding the ne-grained patterns of how individuals interact was essential to develop an effective public health control plan. 27 The response to the epidemic was not only in the timely treatment of patients or close contacts but also in preventive monitoring and management of risk groups. Some shermen in the two cities would buy sh from shing boats at sea. These overseas shing boats were mainly from countries where the COVID-19 epidemic was more serious. The purchased shery may be contaminated by the virus and then brought back by cold chain transportation on the shing boat. At the same time, shermen may come into contact with people infected with COVID-19 overseas. Regular nucleic acid tests and health declaration management were carried out on shermen.
Response to COVID-19 pandemic as protective barriers to each other Macau implemented dynamically adjusted isolation and quarantine measures for foreign immigrants. In key links such as airport transshipment, designated hospital treatment and isolation management, the entire chain of management from border to home door was realized, and the border defense line was strengthened. This border defense line provided a barrier for Zhuhai, which had no international ights. As a tourist city connected to mainland China, Zhuhai quarantined people from high-risk areas in the mainland for the purpose of traveling to Macau, providing a barrier for Macau. For example, in the early stage, a one-time full-coverage nucleic acid test was performed on all personnel from Hubei in Zhuhai to detect suspected cases as soon as possible. Zhuhai established a three-person health management team in the community to conduct grid management for residents in the jurisdiction.
In addition, the two cities strengthened the isolation management of Hong Kong immigrants, timely detection and investigation of patients with fever/cough or patients with travel history in risky areas by medical institutions, and regular nucleic acid inspections of all medical staff. Strictly implemented measures were performed, such as wearing masks, temperature checks, and health QR codes checked for public places and public transportation 28 in densely crowded individuals.

Limitations
Because the source of infection and transmission chain of some cases were not clear, the judgment of local infection cases may be biased. Adjustment of the measures, especially the details, was very frequent. Due to space limitations, only the representative ones were listed.

Conclusions
In the prevention and control of the COVID-19 epidemic in Macau and Zhuhai, both had zero tolerance for COVID-19 cases and adopted a suppression strategy. They responded quickly, with measures in place, and cooperated and communicated in a timely manner. There was no community transmission of local cases, and the control effect was very obvious. After the epidemic stabilized and the comprehensive promotion of the resumption of work and production, the two cities implemented uni ed normalization measures that were basically consistent and successfully implemented the prevention and control strategy of coccities.

Settings
The average permanent population was 679,600 in 2019 in Macau, and the population density was 20400 people per square kilometer. Macau is one of the most densely populated areas in the world and one of the world's four largest gambling cities, with up to 38 million tourists per year. 29 Macau's economy is highly export-oriented. Its pillar industries are mainly gaming, tourism, hotels and casinos and are closely linked to the international economy.

Data collection
The period for obtaining data was from January 1, 2020, to December 31, 2020. The data of con rmed cases in Macau came from the public announcement of the Health Bureau of Macau. 34 The data of con rmed cases in Zhuhai came from China's infectious disease report information management system. The data on Macau inbound visitors who came from mainland China were obtained from the Macau Statistics Bureau. The prevention and control strategy adopted by Macau came from the o cial website of the Macau Department of Health. The prevention and control strategy that Zhuhai adopted came from the municipal government's epidemic prevention and control headquarters.

Classi cation of 3 Periods
To better re ect the epidemic characteristics of COVID-19 in Macau and Zhuhai and the corresponding coordinated intervention measures, this time was divided into three periods (Figure 2). The rst period was the early stage of the COVID-19 epidemic in Wuhan, as the rst place of the clustered cases was located and spread outward. Macau and Zhuhai jointly responded to the outbreak caused by the import of mainland China, especially from Wuhan, and curbed the further spread of indigenous infection cases.
The second period was the stage of the global pandemic. Macau and Zhuhai cooperated to deal with imported cases outside of mainland China, including foreign countries and Hong Kong, and further improved the normalized prevention and control mechanism. In the third period, which had an overlap with the second period under normalized prevention and control measures, the two places communicated with each other, gradually returning to normal work and life and economic recovery. From the perspective of three periods, we analyzed the characteristics of the epidemic in different periods and the strategies and measures adopted.  Health QR Code of Zhuhai and Macau The "green code" means that personnel can freely enter and exit public places, and their normal movement will not be restricted by epidemic prevention and control measures. The "yellow code" refers to persons with fever symptoms, persons with a history of living in medium-risk and high-risk areas, and those who are required to undergo nucleic acid testing for the new coronavirus according to regulations. The "red code" refers to con rmed patients, suspected patients, asymptomatic infected persons and their close contacts; persons who have lived abroad in the past 14 days; persons who are required to undergo centralized quarantine or home medical observation according to regulations, etc. The "yellow code" and "red code" were not allowed to pass through the customs gate.