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The epidemiology of reverse transmission of COVID-19 in Gansu Province, China.

ABSTRACT: Background:The transmission of COVID-19 is about to come under control within China, however, an emerging challenge to the Chinese authorities is reverse transmission due to COVID-19 patients/carriers evacuating from overseas to China. Methods:We analysed the epidemiological characteristics of 311 Chinese citizens evacuated from Iran. All confirmed COVID-19 cases amongst the returnees were displayed by the spatial distribution pattern of the extent of COVID-19 infection. Results:Characteristics that differed significantly amongst these returnees compared to the original infected cohorts in Gansu were mean age, occupation and sex. Differences observed between infected patients and non-patients amongst returnees were age, sex, race, occupation, the use of facemasks, and residential situation in Iran. The clinical features that were significantly related to infection were chill, shortness of breath, chest pain and nausea. Spatial distribution pattern analysis indicated that infected returnees had resided within Iranian provinces that had experienced high levels of COVID-19. The spatial distribution of the original homes of these returnees before departure for Iran demonstrated that returnees will largely return to northwest China, to regions that have only experienced low levels of infection within China. Conclusion:Blocking the reverse transmission of COVID-19 is critical in preventing a secondary outbreak of COVID-19.

SUBMITTER: Fan J

PROVIDER: S-EPMC7215163 | biostudies-literature | 2020 Sep-Oct

REPOSITORIES: biostudies-literature

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The epidemiology of reverse transmission of COVID-19 in Gansu Province, China.

Fan Jingchun J Liu Xiaodong X Shao Guojun G Qi Junpin J Li Yi Y Pan Weimin W Hambly Brett D BD Bao Shisan S

Travel medicine and infectious disease 20200512

<h4>Background</h4>The transmission of COVID-19 is about to come under control within China, however, an emerging challenge to the Chinese authorities is reverse transmission due to COVID-19 patients/carriers evacuating from overseas to China.<h4>Methods</h4>We analysed the epidemiological characteristics of 311 Chinese citizens evacuated from Iran. All confirmed COVID-19 cases amongst the returnees were displayed by the spatial distribution pattern of the extent of COVID-19 infection.<h4>Result ...[more]

PMID: 32407893

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Project description:ImportanceMuch remains unknown about the transmission dynamics of COVID-19. How the severity of the index case and timing of exposure is associated with disease in close contacts of index patients with COVID-19 and clinical presentation in those developing disease is not well elucidated.ObjectivesTo investigate the association between the timing of exposure and development of disease among close contacts of index patients with COVID-19 and to evaluate whether the severity of the index case is associated with clinical presentation in close contacts who develop COVID-19.Design, setting, and participantsThis study used a large, population-based cohort of 730 individuals (index patients) who received a diagnosis of COVID-19 in Zhejiang Province, China, from January 8 to July 30, 2020, along with a contact tracing surveillance program. Field workers visited 8852 close contacts of the index patients and evaluated them for COVID-19 through August 2020. A timeline was constructed to characterize different exposure periods between index patients and their contacts.Main outcomes and measuresThe primary outcome was the attack rate of COVID-19, defined as the total number of new COVID-19 cases diagnosed among contacts of index patients divided by the total number of exposed contacts. A secondary outcome was asymptomatic clinical presentation among infected contacts. Relative risks were calculated to investigate risk factors for COVID-19 among contacts and asymptomatic clinical presentation among infected contacts.ResultsAmong 8852 close contacts (4679 male contacts [52.9%]; median age, 41 years [interquartile range, 28-54 years]) of 730 index patients (374 male patients [51.2%]; median age, 46 years [interquartile range, 36-56 years]), contacts were at highest risk of COVID-19 if they were exposed between 2 days before and 3 days after the index patient's symptom onset, peaking at day 0 (adjusted relative risk [ARR], 1.3; 95% CI, 1.2-1.5). Compared with being exposed to an asymptomatic index patient, the risk of COVID-19 among contacts was higher when they were exposed to index patients with mild (ARR, 4.0; 95% CI, 1.8-9.1) and moderate (ARR, 4.3; 95% CI, 1.9-9.7) cases of COVID-19. As index case severity increased, infected contacts were less likely to be asymptomatic (exposed to patient with mild COVID-19: ARR, 0.3; 95% CI, 0.1-0.9; exposed to patient with moderate COVID-19: ARR, 0.3; 95% CI, 0.1-0.8).Conclusions and relevanceThis cohort study found that individuals with COVID-19 were most infectious a few days before and after symptom onset. Infected contacts of asymptomatic index patients were less likely to present with COVID-19 symptoms, suggesting that quantity of exposure may be associated with clinical presentation in close contacts.

Project description:Hepatitis B is a major global public health threat. According to China's National Notifiable Disease Reporting System (NNDRS), Gannan Tibetan Autonomous Prefecture (Gannan) had the highest incidence of hepatitis B in Gansu Province during 2004 to 2016. We evaluated NNDRS hepatitis B case reports from Gannan to determine accuracy of diagnosis and to understand factors associated with inaccuracy. We reviewed medical records with hepatitis B diagnosis hospitalized in seven county hospitals in Gannan between January 1, 2016 and July 31, 2017. Using national "Classification and Diagnostic Procedures for Hepatitis B," we independently reclassified the diagnoses. We determined the positive predictive value (PPV) of reported hepatitis B cases. We investigate clinicians' understanding of the diagnostic and reporting criteria for hepatitis B by questionnaire. We reviewed and re-categorized 400 inpatients reported. Sixteen cases had been reported as acute hepatitis B, but on re-categorization, none were acute hepatitis B cases. PPVs for chronic hepatitis B and unclassified hepatitis B cases were 66% and 15% respectively; 327 (82%) of the reported hepatitis B cases were inaccurately classified; 261 were carriers, 59 were reported previously, and 7 did not have hepatitis B. The actual incidence of hepatitis B in Gannan in 2016 was estimated to be 19/100,000, significantly below the reported incidence of 106/100,000. Among reported cases, 81% had been tested for Alanine aminotransferase, 52% for hepatitis C antibody, 80% with liver ultrasound, 32% for hepatitis A antibody, and 7% for hepatitis B virus (HBV) DNA. Not all cases were tested for anti-HBc IgM or hepatitis E antibody or had a liver biopsy. In the knowledge test, 56% of clinicians accurately diagnosed three simulated cases of acute hepatitis B, and 17% correctly diagnosed two simulated cases chronic hepatitis B; 22% knew that "a client with only HBsAg positivity need not be reported." The falsely high incidence in Gannan was due to diagnostic and reporting inaccuracies. We recommend that clinicians and laboratorians receive additional training in hepatitis B diagnostic criteria and reporting standards, including appropriate use of IgM anti-HBc tests. Hepatitis B surveillance data should be periodically reviewed and evaluated for accuracy.

Dataset Information

The epidemiology of reverse transmission of COVID-19 in Gansu Province, China.

Publications

The epidemiology of reverse transmission of COVID-19 in Gansu Province, China.

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