Epidemiological Characteristics and Coping Strategies of COVID-19 in Shandong Province, China

Background: The COVID-19 spread from Hubei Province to the whole country and even many countries in the world, which has greatly impacted the public health(cid:0)economic and social development in China and the world. This study aims to investigate the epidemiological characteristics of COVID-19 in Shandong Province, analyze the incidence trends, and explore the coping strategies for providing the basis and reference for COVID-19 epidemic prevention and control. Methods: Descriptive analysis was performed for epidemiological characteristics of con�rmed COVID-19 cases from Jan. 21, 2020 to Feb. 15, 2020, in Shandong Province, and the spatiotemporal distribution of con�rmed cases was drawn. Results: As of Feb. 15, 2020, there were 537 con�rmed cases in Shandong Province and the cumulative incidence was 0.53/100000. The daily number of new con�rmed cases showed a trend of �rst increase and then decrease, and the increase rate of the cumulative con�rmed cases showed a downward trend. The severe rate, critical rate, cured rate and fatality rate were 2.98%, 2.23%, 30.54%, and 0.37%. Con�rmed cases were more Males than females, and the infected patients covered all age groups. The cumulative number of con�rmed cases of the resident population in the province has gradually exceeded that of the population from other places to Shandong, and the number of patients who had a history of close contact with con�rmed cases has signi�cantly increased over time. Qingdao had the largest number of con�rmed cases. Conclusions: Our �ndings analyzed the early period of the epidemic in Shandong Province, which provide a novel insight for epidemic prevention and control.


Background
Since December 2019, cases of viral pneumonia of unknown causes were detected in Wuhan City, Hubei Province, China, and the virus was subsequently con rmed to be a new type of coronavirus that had never been found in humans before [1].The virus began to spread from person to person in close contacts since December 2019 [2,3], and the National Health Commission included it in the National Category B Infectious Diseases and adopted prevention and control measures following Category A Infectious Diseases [4,5].The World Health Organization (WHO) o cially identi ed the epidemic as a "Public Health Emergency of International Concern, PHE-IC" on January 31, and on February 11, 2020, the new coronavirus was named Coronavirus disease-2019 (COVID- 19)[6].
The outbreak spread from Hubei Province to the whole country and even many countries in the world, which caused a major impact on public health,economic and social development in China and the world.Since the rst con rmed case of COVID-19 pneumonia appeared in Shandong Province on January 21, a total of 537 cases were con rmed as of February 15.The situation was relatively severe and prevention and control measures needed to adapt.

Overview of the COVID-19 epidemic situation in Shandong
The rst con rmed case of COVID-19 reported in Shandong Province on January 21, 2020.As of 24:00 on February 15, a total of 537 con rmed cases were reported.There were con rmed patients in all cities except Dongying City.Among them, Qingdao City (57 cases) and Jining City (51 cases) had the largest number of con rmed cases, followed by Jinan City (47 cases).The province's incidence rate was 0.53 per In this article, we reviewed and analyzed the COVID-19 outbreak in Shandong Province, and we proposed emergency strategies and measures for the outbreak.the objective of the research is to provide a scienti c basis and reference for the prevention and control of the COVID-19 outbreak.

Data source
The data of the COVID-19 epidemic in Shandong province was retrieved online, mainly from the Shandong Provincial Health Commission and the o cial websites of the Municipal Health Commissions; and the data from January 21, 2020, to February 15, 2020, was collected.

Diagnostic criteria and clinical types of COVID-19
The diagnostic criteria and clinical types(mild, moderate, severe and critical) of con rmed cases were based on the "Novel Coronavirus Pneumonia Diagnosis and Treatment Plan (Trial Sixth Edition)" [7] and the "Novel Coronavirus Pneumonia Prevention and Control Plan (Fifth Edition)"[8]issued by the China National Health Commission.

Variables
The COVID-19 epidemic, demographic data, mainly including the number of daily and cumulative con rmed cases, the number of severe and critical cases, the number of cured and fatality cases, the travel,residence and contact history and the gender, age of patients, et cetera were reviewed.The incidence rate was calculated based on the number of permanent residents in Shandong province according to the "Shandong Statistical Yearbook-2019" [9].

Data analysis
Descriptive analysis method was applied to analyze the overall situation of the epidemic in Shandong Province, to review the epidemiology of COVID-19 outbreak; the enumeration data were shown as the form of rate and composition ratio, and we calculated the incidence rate, chain growth rate and ratio of severe and critical patients, cured rate and fatality rate and others.We used Microsoft Excel 2016 to establish a database to analyze data and we used Python's Data Visualization Module Pyecharts and other tools to draw epidemic maps, and analyzed the temporal and spatial distribution of con rmed cases of COVID-19 in Shandong Province.100,000, and more than half of cities in Shandong the incidence rate higher than 0.53 per 100,000(Shandong average rate).The data is shown in Table 1.The growth trend of the con rmed COVID-19 cases in Shandong Since the rst con rmed case appeared in Shandong Province on January 21, the number of new con rmed cases per day was up to 45 on February 5, and gradually declined since then.According to the date, the number of con rmed cases in the last three days were 13, 11, and 7 respectively; the number of con rmed cases gradually increased over time, and the overall growth trend after February 10 was signi cantly slower than before(Fig. 1 ).Judging from the growth rate of the cumulative con rmed cases, there was a large uctuation before January 27, and thereafter it had been in a downward trend(Fig.2 ).
The statistics of con rmed cases base on category (Severe, critical, fatality, cured, etc.) The cumulative number con rmed cases of severe symptoms had a gradual increase before February 8.The number of critical cases increased day by day since January 30, but the overall uctuation was relatively small.After the rst cured patients on January 30, the cumulative number of cured patients gradually increased, and the growth rate gradually increased over time.As of February 15th, Shandong Province had a total of 16 cases of severe illness and 12 cases of critical.The rates of severe and critical patients were 2.98% and 2.23% respectively;164 cases were cured, and 2 cases died.The cured rate and fatality rates were 30.54% and 0.37% respectively.As Fig. 3 shows.

Epidemiological characteristics of the con rmed cases of COVID-19 in Shandong
Gender and age distribution of con rmed cases of COVID-19 in Shandong Province (Fig. 4): Among the con rmed cases, there were 299 male patients (55.68%) and 238 female patients (44.32%).The number of male cases was higher than that of female, and the male to female ratio was 1.26:1.From the perspective of age distribution, the oldest con rmed case was 91 years old, the youngest was only 9 months old, and the average age was 43 years old.There were con rmed patients in all age groups, and most of the patients were aged 30-59 years old; There were more females than males in patients who 60 years old and above, and more males than females who under 60 years old.
The trend of con rmed cases of permanent population in Shandong and population came to Shandong from other places(Fig.5): According to the population information of con rmed patients provided by the o cial website of the Shandong Provincial Health Commission, from January 21 to February 1,the number of con rmed cases of population to Shandong from other places was higher than the con rmed cases of permanent population.On February 2, the number was the same.From February 3 to February 15, the cumulative number of con rmed cases in the province's permanent population exceeded the number of con rmed cases of population came to Shandong.Moreover, the gap between the two was gradually increasing, showing that the cumulative number of cases in this province had a signi cant upward trend, and the number of con rmed cases in the population to Shandong from other places tended to be at.
Contact, travel and residence history of con rmed cases of COVID-19 in Shandong Province(Fig.6): From January 21 to February 6, the cumulative number of con rmed cases with a history of contact in Hubei or with a history of travel or residence in provinces other than Shandong and Hubei was higher than that of con rmed cases from January 21 to February 6,and the latter only took two days to achieve a surpass in number, and the gap gradually widened from February 8 to February 15.Although the cumulative number of con rmed cases with a history of contact in Hubei or provinces other than Shandong was increasing, the growth rate had gradually slowed since February 8.
Temporal and spatial distribution of con rmed cases Qingdao City reported the rst con rmed case of COVID-19 on January 21 (Fig. 7a), and then cases in other cities were con rmed; on January 24, More than half of the cities in Shandong had con rmed cases (Fig. 7b); as of January 27, except for Dongying City, Shandong Province had con rmed cases in all cities (Fig. 7c); on February 5, the number of cases in Shandong reached a peak (45 cases, Fig. 7d), and the daily increase in the number of con rmed cases had slowed since February 10 (Fig. 7e); by February 15,The 6 cities Jinan, Qingdao, Yantai, Weifang, Jining Linyi had more con rmed cases, with more than 40 cases (Fig. 7f).

Discussion
The rst con rmed patient with COVID-19 in Shandong Province was a 37-year-old male from Wuhan who worked in Rizhao City.He was treated in Rizhao and Qingdao due to fever and other symptoms.He had lived in Wuhan within two weeks before and he was admitted to the hospital for isolation and treatments.On January 21,the expert group evaluated and con rmed that he had infected COVID-19.At the same time, the Shandong Novel Coronavirus Leading Group immediately arranged epidemic prevention and control works and emphasized the on-duty requirements of key positions, and strictly implemented the "daily report, zero reports" rules.Since then, in the face of the gradual increase in the number of con rmed cases per day, Shandong Province launched a Level I response to major public health emergencies on January 24 [10] to mobilize the entire province to curb the spread of the virus.Over time, the number of daily con rmed cases in Shandong Province increased to the highest on February 5 and then showed a downward trend.The growth rate of the cumulative con rmed cases uctuated before January 27, but gradually declined from January 28.The stabilization indicates that the incidence of pneumonia caused by the COVID-19 in Shandong Province had slowed down and that the series of prevention and control measures implemented in Shandong Province were effective.
From the above studies, as of February 15th, most of the patients diagnosed with COVID-19 in Shandong Province were mild or moderate.Severe rate is 2.98%, and the fatality rate was 0.37%, which was lower than the number of con rmed cases in Chongqing Province which was 537 Cases in that time [11]; the critical rate was 2.23%, which was lower than that of Shanxi Province [12]; the cured rate was 30.54%, which was higher than the cured rate in Chongqing and Shanxi Province.This might be related to the actual conditions faced by different provinces and cities, and to a certain extent indicated that the diagnosis and treatment measures in Shandong Province were effective.
The results of this study show that there were more males than females in the con rmed cases, and the male-to-female ratio was 1.26:1, which similar to the ndings of Ou Jianming et al. [13] and slightly higher than the research results of COVID-19 Emergency of the Chinese Center for Disease Control and Prevention and Response Mechanism Epidemiology Group [14].Compared with women, men are more mobile and have a wider social network and groups.In the passenger and cargo transportation, logistics, express delivery, and other industries, the number of men employed is signi cantly higher than that of women, so men are more susceptible to infection.In the age distribution, the oldest con rmed case was 91 years old and the youngest was only 9 months.There were infected persons in all age groups, indicating that the virus was generally susceptible to infect all age groups [15].The age of the patients was concentrated in the range of 30-59 years old; most were middle-aged and young people.It may be that this age group is active, socially extensive, and contacts with many people, which may increase the risk of infection.This study also nds that there were more female patients whom more than 60 years of age, and more male patients under 60 years old than female patients, which may be related to differences in male and female physiological characteristics.
Judging from the travel, residence and contact history of con rmed cases, the cumulative number of con rmed cases with a history of travel,residence in other places rather than Shandong and Hubei before February 6 was higher than the cumulative number of con rmed cases with a history of contact in Hubei and a history of close contact with con rmed cases.This was mainly because of the initial outbreak of the epidemic coincided with the Spring Festival.Factors such as the ow of people, vacations, and the increase of the migrant population in a short period provided favorable conditions for the further spread of the epidemic.Studies show that the development of the COVID-19 epidemic or pandemic was related to the level of population mobility [16].Frequent population mobility was extremely conducive to the spread of infectious diseases.After that, the number of patients with a history of close contact with the con rmed case increased rapidly and quickly exceeded the number of cases with a history of living or travel in other places rather than Shandong and Hubei, and a history of contact in Hubei in a short time, indicating that the local epidemic spread rapidly through contact, which gave rise to what Academician Zhong Nanshan said "super spreaders" and second-generation cases [17].By reviewing the case data, it is known that Zhang XX from Weifang, Shandong[18] and Tian XX from Heze, Shandong [19] deliberately concealed their travel, illness, and close contact history, resulting in a total of more than 100 people being isolated and causing a local epidemic and the disease spread rapidly and multiple infections.After February 10, the cumulative number of con rmed cases with a history of travel or residence in other places rather than Shandong and Hubei, a history of contact in Hubei, and a history of close contact with con rmed cases had slowed down, which further illustrated that Shandong Province initiating the highest-level response to detect and control the infection in the rst time was effective.Measures such as blocking possible transmission channels and protecting susceptible populations had effectively curbed the spread of the epidemic.
The Temporal and spatial distribution map of con rmed cases of COVID-19 in Shandong Province shows that during the epidemic, the rst con rmed patient was con rmed in Qingdao, and as of February 15, the city had the highest number of cases in Shandong.As an open coastal city and an economically developed city in northern China, Qingdao was affected by factors such as climate, geography, economy and social culture and dense population and developed transportation, coupled with a large ow of population, were extremely conducive to the spread of the virus.
There were no con rmed patients in Dongying City.The reason was not only that the government and relevant departments took timely and early measures to curb the spread of the epidemic in Dongying, but it might also be due to other factors of Dongying City.For example, comparing with densely populated areas with convenient transportation, Dongying City had a low population density, underdeveloped railway and air transportation, and high per capita GDP and fewer migrant workers, making it less likely to have close contact with people from Hubei.From the perspective of the national epidemic situation, Tibet, Qinghai, and other western regions in China; there were sparsely populated areas and relatively underdeveloped transportation had fewer con rmed cases.The characteristics of the epidemic in Dongying were also consistent with some of the characteristics of the national epidemic distribution.Therefore, taking targeted joint prevention and control measures according to the characteristics of the area is an effective means to reduce the incidence the outbreak.
Although the research results show that the incidence of COVID-19 in Shandong Province has slowed down, it is also facing pressure from resuming work, resuming production, and returning to school.Besides, the global pandemic situation is severe and the vaccine is still in the experimental stage [20], COVID-19 prevention and control still cannot be relaxed.Therefore, based on the epidemiological characteristics of the COVID-19 and the latest developments and changes of the epidemic or pandemic, the future response strategies for prevention and control are given as follow: First and foremost, construct a multi-level public security intelligent monitoring, early warning, and control system.Further expand the monitoring network, improve big data analysis technology, enhance early monitoring and early warning capabilities, and realize real-time intelligent epidemic warning [21][22][23].
Improve the real-time query system for epidemic risk levels and comprehensively promote the use of health passcodes (or health virtual pass cards) across the country to further accurately identify people form high, medium, and low-risk areas.The construction of monitoring, early warning, and control system for diseases of unknown origin and emerging infectious diseases should be established.
Moreover, scienti cally and rationally allocate and utilize existing medical and health resources, and improve the joint prevention and control work mechanism.For large general hospitals and infectious disease hospitals, training bases for epidemic prevention and control should be established; emergency management departments, disease control departments, lower-level hospitals, and primary health institutions need work together to conduct regular epidemic prevention and control-related training and drills to strengthen and improve multi-departmental collaboration and upper-lower level linkage mechanisms.For county-level general hospitals, independent infectious disease departments should be set up, and existing outpatient clinics and wards should have the ability to be transformed base on the combining peace and war principles, and should equip with negative pressure wards, and negative pressure ambulances to ensure that if an outbreak occurs, it can be reached quickly for emergency treatment of critically ill patients.For primary health institutions such as village clinics and community health service centers (stations), efforts should be made to build fever screening sentinels to enable them to have early screening capabilities, give full play to the role of sentinel surveillance against the epidemic or pandemic, and preliminary screening, identi cation, treatments, and referral of fever patients are effectively carried out to effectively "early detect and report" the outbreak, which is more conducive to the epidemic prevention and control.For centers for disease control (CDC), it is necessary to establish a certain scale of epidemiological investigation teams in each county and district, and increase investment in efforts to laboratory construction, and support to do more scienti c researches to accelerate vaccine research and development [24].
Besides, effectively carry out the epidemic investigation, prevention and control of the ow of population, implement strict entry-exit inspection and quarantine measures, continue to implement travel registration and body temperature testing systems.It is necessary to continue to strengthen the disinfection and ventilation of public places, adopt exible working hours to reduce the number of people gathering.[25].
Last but not the least, attach importance to social mobilization, strengthen health education, communication, increase the public's initiative and motivation for epidemic prevention and anti-epidemic, and encourage the public to take the initiative to pay attention to infectious diseases and epidemicrelated information and report the epidemic to relevant professional agencies in time.Governments and relevant professional institutions should incorporate the social risk early warning force of major epidemics into the formal public opinion monitoring and release system so as to timely verify and scienti cally screen the information.It is necessary for us to continue to strengthen the breadth and depth of health education[26], increase public awareness of the COVID-19.Carry out online health education and consulting services to enhance the public's protection awareness [27].

Conclusions
In short, our ndings analyzed the early period of the epidemic in Shandong Province, which provide a novel insight for epidemic prevention and control.At present, the global epidemic situation is still severe, but vaccines have not yet been put into use in large quantities.Therefore, nding the coping strategies for epidemic prevention and control is still the top priority of all future tasks.

Figures
Page 13/21 The trend of daily con rmed cases and cumulative con rmed cases of COVID-19 in Shandong Province The trend of daily con rmed cases and cumulative con rmed cases of COVID-19 in Shandong Province The growth rate of the cumulative con rmed cases of COVID-19 in Shandong Province The growth rate of the cumulative con rmed cases of COVID-19 in Shandong Province Gender and age distribution of con rmed cases of COVID-19 in Shandong Province The trend of cumulative con rmed cases of permanent population and population came to Shandong from other places Page 18/21 The trend of cumulative con rmed cases of permanent population and population came to Shandong from other places Figure 6 contact, travel and residence history of con rmed cases of COVID-19 in Shandong Figure 6 contact, travel and residence history of con rmed cases of COVID-19 in Shandong Temporal and spatial distribution of con rmed cases of COVID-19 in various cities in Shandong Province Note: The designations employed and the presentation of the material on this map do not imply the expression of any opinion whatsoever on the part of Research Square concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.This map has been provided by the authors.
Temporal and spatial distribution of con rmed cases of COVID-19 in various cities in Shandong Province Note: The designations employed and the presentation of the material on this map do not imply the expression of any opinion whatsoever on the part of Research Square concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.This map has been provided by the authors.

Table 1
Number of con rmed cases and cumulative incidence of COVID-19 in various regions of