The Impact of Multilateral Imported Cases of COVID-19 on the Epidemic Control in China

While the spread of COVID-19 in China is under control,the pandemic is developing rapidly around the world.Due to the normal migration of population,China is facing the high risk from imported cases.The potential specific medicine and vaccine are still in the process of clinical trials.Currently,controlling the impact of imported cases is the key to prevent new outbreak of COVID-19 in China.In this paper,we propose two impulsive systems to describe the impact of multilateral imported cases of COVID-19.Based on the published data,we simulate and analyze the epidemic trends under different control strategies.In particular,we compare four different scenarios and show the corresponding medical burden.The results can be useful in designing appropriate control strategy for imported cases in practice.

A Case Series of Olfactory Dysfunction in Imported COVID-19 Patients:A 12-Month Follow-Up Study

Objective The scientific community knows little about the long-term influence of coronavirus disease2019(COVID-19) on olfactory dysfunction(OD). With the COVID-19 pandemic ongoing worldwide, the risk of imported cases remains high. In China, it is necessary to understand OD in imported cases.Methods A prospective follow-up design was adopted. A total of 11 self-reported patients with COVID-19 and OD from Xi’an No. 8 Hospital were followed between August 19, 2021, and December 12, 2021.Demographics, clinical characteristics, laboratory and radiological findings, and treatment outcomes were analyzed at admission. We surveyed the patients via telephone for recurrence and sequelae at the1-, 6-, and 12-month follow-up.Results Eleven patients with OD were enrolled;of these, 54.5%(6/11) had hyposmia and 45.5%(5/11)had anosmia. 63.6%(7/11) reported OD before or on the day of admission as their initial symptom;of these, 42.9%(3/7) described OD as the only symptom. All patients in the study received combined treatment with traditional Chinese medicine and Western medicine, and 72.7%(8/11) had partially or fully recovered at discharge. In terms of OD recovery at the 12-month follow-up, 45.5%(5/11) reported at least one sequela, 81.8%(9/11) had recovered completely, 18.2%(2/11) had recovered partially, and there were no recurrent cases.Conclusions Our data revealed that OD frequently presented as the initial or even the only symptom among imported cases. Most OD improvements occurred in the first 2 weeks after onset, and patients with COVID-19 and OD had favorable treatment outcomes during long-term follow-up. A better understanding of the pathogenesis and appropriate treatment of OD is needed to guide clinicians in the care of these patients.

An Insight of the First Community Infected COVID-19 Patient in Beijing by Imported Case: Role of Deep Learning-Assisted CT Diagnosis

In the era of coronavirus disease 2019(COVID-19)pandemic,imported COVID-19 cases pose great challenges to many countries.Chest CT examination is considered to be complementary to nucleic acid test for COVID-19 detection and diagnosis.Wie report the first community infected COVID-19 patient by an imported case in Beijing,which manifested as nodular lesions on chest CT imaging at the early stage.Deep Learning(DL)-based diagnostic systems quantitatively monitored the progress of pulmonary lesions in 6 days and timely made alert for suspected pneumonia,so that prompt medical isolation was taken.The patient was confirmed as COVID-19 case after nucleic acid test,for which the community transmission was prevented timely.The roles of DL-assisted diagnosis in helping radiologists screening suspected COVID cases were discussed.

Serological Study of An Imported Case of Middle East Respiratory Syndrome and His Close Contacts in China, 2015

The first imported Middle East respiratory syndrome （MERS） case in China was identified in May 2015. We determined the kinetics of antibody （IgG and IgM） and neutralizing antibodies against MERS-coronavirus （MERS-CoV） in this case before discharge. Moreover, no seroconversion was found among 53 close contacts by anti-MERS IgG antibody enzyme-linked immunosorbent assay （ELISA） of paired serum samples. These findings suggest that neither community nor nosocomial transmission of MERS-CoV occurred in China.

Dengue outbreaks in Taiwan, 1998-2017: Importation, serotype and temporal pattern

Objective: To ascertain the role of imported cases and serotypes on dengue outbreaks in Taiwan which have been sporadic yet highly volatile during the past two decades, exhibiting record-breaking magnitude in recent years. Methods: Confirmed case and serotype data from Taiwan Centers for Disease Control during 1998-2017 were fully examined, with fitting of weekly and daily case data of each city/county to a mathematical model to pinpoint the waves of cases and their locations. Moreover, we quantify the timing of turning point and transmission potential of each wave and determine its circulating serotype, to ascertain any pattern or connection between the variations in circulating serotypes and the magnitude/transmissibility of outbreak. Results: While the number of imported case increased steadily during past two decades, the yearly number of indigenous cases fluctuated wildly. Moreover, while yearly percentages of serotypes for imported cases remains steady, that of indigenous cases does not exhibit any clear pattern. There was at least one wave of reported cases somewhere in Taiwan every year from 1998 to 2015, except in 2016-2017. The effective reproduction number R for all waves in all locations ranged from 1.14 to 2.87, with the exception of two Tainan waves, in 2010(3.95) and 2015(6.84). Four major outbreaks of over 2000 cases reveal circulation of one dominant serotype. Conclusions: Correlation between imported cases and indigenous outbreak prove to be difficult to ascertain, even with the availability of serotype data. However, although there had been occasional co-circulation of serotypes in one location, and for some years with different serotypes circulating in different locations, all major outbreaks of over 2 000 cases during the past two decades are due to circulation of mainly a single serotype, perhaps indicating greater transmission potential with one dominating serotype.

Epidemiological characteristics and temporal-spatial analysis of overseas imported dengue fever cases in outbreak provinces of China, 2005–2019

Background Overseas imported dengue fever is an important factor in local outbreaks of this disease in the mainland of China.To better prevent and control such local outbreaks,the epidemiological characteristics and temporal-spatial distribution of overseas imported dengue fever cases in provincial-level administrative divisions(PLADs)where dengue fever is outbreak in the mainland of China were explored.Methods Using the Chinese National Notifiable Infectious Disease Reporting Information System(CNNDS),we identified overseas imported dengue fever cases in dengue fever outbreak areas in the mainland of China from 2005 to 2019 to draw the epidemic curve and population characteristic distribution of overseas imported cases in each PLAD.Based on spatial autocorrelation analysis of ArcGIS 10.5 and temporal-spatial scanning analysis of SaTScan 9.5,we analyzed the temporal-spatial distribution of overseas imported dengue fever in dengue fever outbreak areas in the mainland of China.Results A total of 11,407 imported cases,mainly from Southeast Asia,were recorded from 2005 to 2019 in these 13 PLADs.Of which 62.1%were imported into Yunnan and Guangdong Provinces.Among the imported cases,there were more males than females,mainly from the 21–50 age group.The hot spots were concentrated in parts of Yunnan,Guangdong and Fujian Provinces.We found the cluster of infected areas were expanding northward.Conclusions Based on the analysis of overseas imported dengue cases in 13 PLADs of the mainland of China from 2005 to 2019,we obtained the epidemiological characteristics and spatial distribution of imported dengue cases.Border controls need to pay attention to key population sectors,such as 21–50 years old men and education of key populations on dengue prevention.There is a need to improve the awareness of the prevention and control of imported cases in border areas.At the same time,northern regions cannot relax their vigilance.

Chikungunya in Zhejiang Province,Southeast China

Background:Chikungunya is emerging and reemerging word-widely in the past decades.It is non-endemic in Zhejiang Province,Southeast China.Aedes albopictus,one of major vectors of chikungunya,is widely-distribution in Zhejiang,and autochthonous transmission is possible after introducing chikungunya virus.Methods:Retrospectively collected the epidemiological,clinical and genetic data of chikungunya and conducted the descriptive analysis and gene sequence analysis.Results:From 2008 to 2022,29 chikungunya cases,including 26 overseas imported and 3 local cases,were reported and no cases died of chikungunya.More than half of the imported cases(53.85%)were from Southeast Asia.Seasonal peak of the imported cases was noted between August and September,and 42.31%cases onset in those 2 months.Eight prefecture-level cities and 16 counties reported cases during the study period,with Jinghua(27.59%)and Hangzhou(24.14%)reporting the largest number of cases.The 3 local cases were all reported in Qujiang,Quzhou in 2017.For imported cases,the male-female gender ratio was 2.71:1,20-30 years old cases(46.15%)and commercial service(42.31%)accounted for the highest proportion.Clinically,fever(100%),fatigue(94.44%),arthralgia(79.17%),headache(71.43%)and erythra(65.22%)were the most common reported symptoms.Eight whole-genome sequences were obtained and belonged to East/Central/South African(ECSA)or Asian genotype.Conclusions:With the change of immigration policy,the surveillance of chikungunya should be strengthened and the ability of the case discovery and diagnosis should be improved in Zhejiang in the post-COVID-19 era.

The patterns and driving forces of dengue invasions in China

Background Global connectivity and environmental change pose continuous threats to dengue invasions from worldwide to China.However,the intrinsic relationship on introduction and outbreak risks of dengue driven by the landscape features are still unknown.This study aimed to map the patterns on source-sink relation of dengue cases and assess the driving forces for dengue invasions in China.Methods We identified the local and imported cases(2006–2020)and assembled the datasets on environmental conditions.The vector auto-regression model was applied to detect the cross-relations of source-sink patterns.We selected the major environmental drivers via the Boruta algorithm to assess the driving forces in dengue outbreak dynamics by applying generalized additive models.We reconstructed the internal connections among imported cases,local cases,and external environmental drivers using the structural equation modeling.Results From 2006 to 2020,81,652 local dengue cases and 12,701 imported dengue cases in China were reported.The hotspots of dengue introductions and outbreaks were in southeast and southwest China,originating from South and Southeast Asia.Oversea-imported dengue cases,as the Granger-cause,were the initial driver of the dengue dynamic;the suitable local bio-socioecological environment is the fundamental factor for dengue epidemics.The Bio8[odds ratio(OR)=2.11,95%confidence interval(CI):1.67–2.68],Bio9(OR=291.62,95%CI:125.63–676.89),Bio15(OR=4.15,95%CI:3.30–5.24),normalized difference vegetation index in March(OR=1.27,95%CI:1.06–1.51)and July(OR=1.04,95%CI:1.00–1.07),and the imported cases are the major drivers of dengue local transmissions(OR=4.79,95%CI:4.34–5.28).The intermediary effect of an index on population and economic development to local cases via the path of imported cases was detected in the dengue dynamic system.Conclusions Dengue outbreaks in China are triggered by introductions of imported cases and boosted by landscape features and connectivity.Our research will contribute to developing nature-based solutions for dengue surveillance,mitigation,and control from a socio-ecological perspective based on invasion ecology theories to control and prevent future dengue invasion and localization.

Epidemiological characteristics of Plasmodium malariae malaria in China:a malaria that should not be neglected post elimination

Background Plasmodium malariae was always neglected compared withP.falciparum andP.vivax.In the present study,we aimed to describe the epidemiology of reported cases infected withP.malariae in the past decade to raise awareness of the potential threat of this malaria parasite in China.Methods Individual data of malaria cases infected withP.malariae reported in China in the past decade were collected via the China Information System for Disease Control and Prevention and Parasitic Diseases Information Reporting Management System,to explore their epidemiological characteristics.Pearson Chi-square tests or Fisher’s Exact Test was used in the statistical analysis.Results From 2013 to 2022,a total of 581P.malariae cases were reported in China,and mainly concentrated in 20-59 years old group(P<0.001),and there was no significant trend in the number of cases reported per month.Moreover,four kinds ofP.malariae cases were classified,including 567 imported cases from 41 countries in 8 regions and distributed in 27 provinces(autonomous regions,municipalities)in China,six indigenous cases in a small outbreak in Hainan,seven recurrent cases in Guangdong and Shanghai,and one induced case in Shanghai,respectively.In addition,only 379 cases(65.2%)were diagnosed as malaria on the first visit(P<0.001),and 413 cases(71.1%)were further confirmed asP.malariae cases(P=0.002).Meanwhile,most cases sought healthcare first in the health facilities at the county and prefectural levels,but only 76.7%(161/210)and 73.7%(146/198)cases were diagnosed as malaria,and the accuracy of confirmed diagnosis as malaria cases infected withP.malariae was only 77.2%(156/202)and 69.9%(167/239)in these health facilities respectively.Conclusions Even though malaria cases infected withP.malariae didn’t account for a high proportion of reported malaria cases nationwide,the threat posed by widely distributed imported cases,a small number of indigenous cases,recurrent cases and induced case cannot be ignored in China.Therefore,it is necessary to raise awareness and improve the surveillance and response to the non-falciparum species such asP.malariae,and prevent the reestablishment of malaria transmission after elimination.