Contact patterns between index patients and their close contacts and assessing risk for COVID-19 transmission during different exposure time windows: a large retrospective observational study of 450 770 close contacts in Shanghai
Introduction To characterise age-mixing patterns among index cases and contacts of COVID-19, and explore when patients are most infectious during the disease process.Methods This study examined all initial 90 885 confirmed index cases in Shanghai and their 450 770 close contacts. A generalised addit...
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BMJ Publishing Group
2024-07-01
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| Series: | BMJ Public Health |
| Online Access: | https://bmjpublichealth.bmj.com/content/2/1/e000154.full |
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| author | Weibing Wang Genming Zhao Hao Pan Bo Zheng Chenyan Jiang Yaxu Zheng Huanyu Wu Shenghua Mao Ye Yao Xiaohuan Gong Sheng Lin Bihong Jin Dechuan Kong |
| author_facet | Weibing Wang Genming Zhao Hao Pan Bo Zheng Chenyan Jiang Yaxu Zheng Huanyu Wu Shenghua Mao Ye Yao Xiaohuan Gong Sheng Lin Bihong Jin Dechuan Kong |
| author_sort | Weibing Wang |
| collection | DOAJ |
| description | Introduction To characterise age-mixing patterns among index cases and contacts of COVID-19, and explore when patients are most infectious during the disease process.Methods This study examined all initial 90 885 confirmed index cases in Shanghai and their 450 770 close contacts. A generalised additive mixed model was used to analyse the associations of the number of close contacts with different demographic and clinical characteristics. The effect of different exposure time windows on the infection of close contacts was evaluated using a modified mixed-effects Poisson regression.Results Analysis of contacts indicated that 82 467 (18.29%; 95% CI 18.17%, 18.42%) were second-generation cases. Our result indicated the q-index was 0.300 (95% CI 0.298, 0.302) for overall contact matrix, and that assortativity was greatest for students (q-index=0.377; 95% CI 0.357, 0.396) and weakest for people working age not in the labour force (q-index=0.246; 95% CI 0.240, 0.252). The number of contacts was 4.96 individuals per index case (95% CI 4.86, 5.06). Contacts had a higher risk if they were exposed from 1 day before to 3 days after the onset of symptoms in the index patient, with a maximum at day 0 (adjusted relative risk (aRR)=1.52; 95% CI 1.30, 1.76). Contacts exposed from 3 days before to 3 days after an asymptomatic index case had a positive reverse transcriptase-PCR (RT-PCR) result had a higher risk, with a maximum on day 0 (aRR=1.48; 95% CI 1.37, 1.59).Conclusions The greatest assortativity was for students and weakest for people working age not in the labour force. Contact in the household was a significant contributor to the infection of close contacts. Contact tracing should focus on individuals who had contact soon before or soon after the onset of symptoms (or positive RT-PCR test) in the index case. |
| format | Article |
| id | doaj-art-788a36f4f32a421bbb0323353e7f9349 |
| institution | Kabale University |
| issn | 2753-4294 |
| language | English |
| publishDate | 2024-07-01 |
| publisher | BMJ Publishing Group |
| record_format | Article |
| series | BMJ Public Health |
| spelling | doaj-art-788a36f4f32a421bbb0323353e7f93492025-01-28T15:45:10ZengBMJ Publishing GroupBMJ Public Health2753-42942024-07-012110.1136/bmjph-2023-000154Contact patterns between index patients and their close contacts and assessing risk for COVID-19 transmission during different exposure time windows: a large retrospective observational study of 450 770 close contacts in ShanghaiWeibing Wang0Genming Zhao1Hao Pan2Bo Zheng3Chenyan Jiang4Yaxu Zheng5Huanyu Wu6Shenghua Mao7Ye Yao8Xiaohuan Gong9Sheng Lin10Bihong Jin11Dechuan Kong12Key Laboratory of Public Health Safety of Ministry of Education, Fudan University, Shanghai, ChinaFudan University, Shanghai, ChinaDepartment of Infectious Disease Control and Prevention, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, ChinaDepartment of Epidemiology, Fudan University School of Public Health, Shanghai, ChinaDepartment of Infectious Disease Control and Prevention, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, ChinaDepartment of Epidemiology, Fudan University School of Public Health, Shanghai, ChinaDepartment of Infectious Disease Control and Prevention, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, ChinaDepartment of Infectious Disease Control and Prevention, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, ChinaDepartment of Medicine II, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, GermanyDepartment of Epidemiology, Fudan University School of Public Health, Shanghai, ChinaDepartment of Infectious Disease Control and Prevention, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, ChinaDepartment of Infectious Disease Control and Prevention, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, ChinaDepartment of Infectious Disease Control and Prevention, Shanghai Municipal Center for Disease Control and Prevention, Shanghai, ChinaIntroduction To characterise age-mixing patterns among index cases and contacts of COVID-19, and explore when patients are most infectious during the disease process.Methods This study examined all initial 90 885 confirmed index cases in Shanghai and their 450 770 close contacts. A generalised additive mixed model was used to analyse the associations of the number of close contacts with different demographic and clinical characteristics. The effect of different exposure time windows on the infection of close contacts was evaluated using a modified mixed-effects Poisson regression.Results Analysis of contacts indicated that 82 467 (18.29%; 95% CI 18.17%, 18.42%) were second-generation cases. Our result indicated the q-index was 0.300 (95% CI 0.298, 0.302) for overall contact matrix, and that assortativity was greatest for students (q-index=0.377; 95% CI 0.357, 0.396) and weakest for people working age not in the labour force (q-index=0.246; 95% CI 0.240, 0.252). The number of contacts was 4.96 individuals per index case (95% CI 4.86, 5.06). Contacts had a higher risk if they were exposed from 1 day before to 3 days after the onset of symptoms in the index patient, with a maximum at day 0 (adjusted relative risk (aRR)=1.52; 95% CI 1.30, 1.76). Contacts exposed from 3 days before to 3 days after an asymptomatic index case had a positive reverse transcriptase-PCR (RT-PCR) result had a higher risk, with a maximum on day 0 (aRR=1.48; 95% CI 1.37, 1.59).Conclusions The greatest assortativity was for students and weakest for people working age not in the labour force. Contact in the household was a significant contributor to the infection of close contacts. Contact tracing should focus on individuals who had contact soon before or soon after the onset of symptoms (or positive RT-PCR test) in the index case.https://bmjpublichealth.bmj.com/content/2/1/e000154.full |
| spellingShingle | Weibing Wang Genming Zhao Hao Pan Bo Zheng Chenyan Jiang Yaxu Zheng Huanyu Wu Shenghua Mao Ye Yao Xiaohuan Gong Sheng Lin Bihong Jin Dechuan Kong Contact patterns between index patients and their close contacts and assessing risk for COVID-19 transmission during different exposure time windows: a large retrospective observational study of 450 770 close contacts in Shanghai BMJ Public Health |
| title | Contact patterns between index patients and their close contacts and assessing risk for COVID-19 transmission during different exposure time windows: a large retrospective observational study of 450 770 close contacts in Shanghai |
| title_full | Contact patterns between index patients and their close contacts and assessing risk for COVID-19 transmission during different exposure time windows: a large retrospective observational study of 450 770 close contacts in Shanghai |
| title_fullStr | Contact patterns between index patients and their close contacts and assessing risk for COVID-19 transmission during different exposure time windows: a large retrospective observational study of 450 770 close contacts in Shanghai |
| title_full_unstemmed | Contact patterns between index patients and their close contacts and assessing risk for COVID-19 transmission during different exposure time windows: a large retrospective observational study of 450 770 close contacts in Shanghai |
| title_short | Contact patterns between index patients and their close contacts and assessing risk for COVID-19 transmission during different exposure time windows: a large retrospective observational study of 450 770 close contacts in Shanghai |
| title_sort | contact patterns between index patients and their close contacts and assessing risk for covid 19 transmission during different exposure time windows a large retrospective observational study of 450 770 close contacts in shanghai |
| url | https://bmjpublichealth.bmj.com/content/2/1/e000154.full |
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